There are two questions here:
The operative word in this verse is חַי (chay = living) which in Ps 69:28 is a noun and not an adjective. Therefore, to translate, "book of the living" is not quite correct - most versions correctly have "book of life".
The meaning of Ps 69:28 appears to suggest that people's names (the pslamist's enemies) be removed from the book of life; that is, those whose names are in the book of life, to have their names removed. There is nothing challenging about this.
There has been much discussion as to whether this verse should be translated as either:
- ... their names have not been written from the founding of the world in the book of life of the Lamb having been slain.
- ... whose names have not been written in the Lamb’s book of life, the Lamb who was slain from the creation of the world.
The Greek is:
οὗ οὐ γέγραπται τὸ ὄνομα αὐτοῦ ἐν τῷ βιβλίῳ τῆς ζωῆς τοῦ Ἀρνίου τοῦ
ἐσφαγμένου ἀπὸ καταβολῆς κόσμου = of whom not having been written the
names of them in the book of life of the Lamb having been slain from
the foundation of the world
Ellicott summs up the tricky translation choice as follows:
There is some doubt about the connection of the words “from the
foundation of the world.” Some connect them with the word “written”:
this would express that the names were written “from the foundation of
the world” in the book. Others connect them with the word “slain”:
this expresses that the Lamb was slain from the foundation of the
world. For the former view, the similar passage in Revelation 17:8 is
cited; but, on the other hand, the phrase “from the foundation of the
world” is connected in other parts of the Bible with certain aspects
of the work of Christ (1 Peter 1:19-20, and John 17:24)
That is, should we understand:
- names written from the foundation of the world? or
- the Lamb was slain from the foundation of the world?
The Greek order of words clearly favors the latter option. Therefore, on this basis, the OP's question, or more correctly, the apparent contradiction, does not exist.
HOWEVER, one might ask the same question with two different text such as Ps 69:28 and Rev 17:8.