I have chosen this question, not only because it is long deserving of being answered but because I feel it touches on my previous answer to the "70 Weeks" question and that therefore I may have something relevant to say. Much like previously, this 12th chapter of Revelation (at least thru V.14), as well as the relevant part of the 9th chapter of Daniel, has long been puzzling and frustrating for me and over the years I have therefore been back and forth on it's interpretation. What I say now is hopefully borne out of educated, not to mention thoughtful perusal.
First of all I think the narrative here, in this chapter, is a flashback, and therefore does not follow on from the narrative of chapter 11. I also think, in particular response to the question, that the two 1260 day time periods, mentioned in Verses 6 & 14, are in fact not in reference to the same event, although they do involve the same "Woman" subject. We are being taken back to the birth of the "Christian" church, which is foreshadowed by the actual birth of Jesus, which was in the Fall of 2 BC (1), and which was signed in the heavens, as per Verse 1, and even Verse 2. Apart from Verses 1, 6 & 14 the "Woman" is also referenced in Verses 4 & 13 and in each verse the Greek language is portraying not only the feminine but also the singular. Four of the five Greek cases are used with regard to the "Definite Article", which precedes all but one of the "Woman" references (V.1., being the exception, where the "Indefinite Article"..a.. is implied in translation). Initially, we have the genitive case (V.4); then the nominative (V.6); accusative (V.13) and dative (V.14), the vocative case is not used with the definite article in Greek. The four different Greek representations of the woman is due to declension of the noun, according to case, gender & number, Greek therefore being a much more exact language than ours and is therefore able to convey a much more exact shade of meaning.
(1) In Luke, it would appear that Jesus was born in 6 AD, Which is ludicrous, at the time of the Census registration, under Quirinius. This is a red herring, as there was an earlier registration (but not an actual Census) in the Fall of 2 BC, in Bethlehem (whereas the later registration was in Roman Syria) and it is during this first registration (also during the time of Quirinius) that Jesus was born...Luke 2:1 thru 5.
Also being signed in heaven, in Verse 3, is the great red dragon, i.e. Satan (we don't need to talk about the seven crowned heads and ten horns for the purposes of this posting), whose tail, in Verse 4, is seen to be sweeping away a third of the stars of heaven, down to the earth, which is most likely a reference to Satan's sympathetic angels, which can only mean potential trouble for the soon to be forming church, not to mention Jesus. Satan (although not yet himself swept out of heaven) is seen to be standing before the woman as she gives birth to a son, a male (Jesus, masculine, singular), who foreshadows the child (early Christian Church, which is portrayed to be singular and neutral in gender in the Greek), in order that he (Satan) may follow Jesus and later devour said child. So, we have the "Woman", a reference not only in the visage of Mary but also in the visage of God's wife, so to speak. We then have the male son, Jesus, and then the early Christian Church as represented by the child, although in Verse 5, the child would appear to collectively represent first Jesus and secondly the early Christian Church, who are then, both, caught away to God and to his throne, over a period of some 33 and one half years (33 to 66 AD), more on this later.
In Verse 6, with regard to the woman, it's very tempting to understand this singular and feminine visage to be a reference to just Mary but let's not forget we are also to understand that we are also talking speculatively about God's wife, who is seen to have fled (past tense) into the Wilderness...."where she had a place prepared by God, so that there she might be nourished for...one thousand two hundred and sixty days... This first of the 1260 day periods would appear to come right, if not immediately, after Christ's death and resurrection in 33 AD but before the Apostles are caught up to heaven. It would therefore appear to refer to the period of the Spring of 33 AD to the Fall of 36 AD, until such time as the first Gentiles are included and thus strengthen the fledgling Christian movement..see Acts 10:45.
Over the next 3 Verses of Rev.12, we are told about war breaking out in heaven (after Jesus has ascended) between Michael (whose name means.."Who is like God") and his angels and the dragon (Satan) and his angels, resulting in Satan and his remaining heavenly angel followers being hurled down to earth. The righteous leading angel here had to be the only Archangel, Michael (forget about all the so called Archangel's in the book of Enoch, which could very well have not been written by Enoch and therefore may well be fiction), the first of God's angels. The only begotten angel probably, making for the argument that Michael and Jesus are one. But that's another story, for another time, maybe.
Verse 10 hears a loud heavenly voice, collective voice of God's heavenly wife presumably, that announces the arrival of God's kingdom with Christ as the ruler, cheering the fact that... "the accuser of our brethren has been thrown down, who accuses them before our God day and night. And they overcame him because of the blood of the lamb and because of the word of their testimony (witnessing), and they did not love their life even to death"...NASB 12:10,11. I think we are talking about Jesus' 12 Apostles (crown of 12 stars..12:1) here, who between the Spring of 33 AD and Fall of 66 AD, witnessed unto death (excepting John), with no fear for their lives, who overcame the Devil's influence because of the blood of the Lamb being fresh in their memories. Verse 12, talks about heaven continuing to rejoice, while there is to be..."Woe to the earth and the sea".
Satan, Verse 13, now on earth, then persecutes the "Woman" that gave birth to the male (masculine, singular, not Neuter as for child, which the NASB mistakenly adds (child that is) to the translation at the end of the verse). Does this mean that we are talking only about Mary here. One has to wonder. Regardless, our woman flies(not fled) into the wilderness, yet again, to her place, where she is fed, yet again, for...a time and times and half a time...Here we have the second 1260 day period, which you should note is described differently here, in Verse 14, and it comes after the brethren have witnessed even to death, which was right up to 66 AD( the beginning of Daniel's "70th Week" as explained in my previous post). I think this second 1260 day period, therefore, may indeed refer to the Fall of 66 AD, through to the Spring/Summer of 70 AD, which, as we all know, culminated in the destruction of Jerusalem and it's Temple......