These are two entirely different groups (though some interpreters link the two):
- Phil 3:2 = the dogs who demand circumcision are the ones trying to gain salvation by the works of the flesh, ie, are Judaizers and do not understand the gospel of grace.
- Phil 1:15-18 = preachers who preach Christ from envy, that is, they preach the gospel of Christ to gain status, or get a following.
Benson says this:
Php 1:15-17. Some indeed preach Christ even of envy — Envying my
success, or envying me that esteem and reputation which I have in the
church, and seeking to gain it to themselves; and strife — Striving to
draw people off from approving me to applaud themselves, and being
desirous to maintain in the church a party that shall oppose me, and
willing to add as many abetters to it as they possibly can.
Barnes suggests this:
Some indeed preach Christ even of envy and strife - What was the
ground of this "envy and strife" the apostle does not mention. It
would seem, however, that even in Rome there was a party which was
jealous of the influence of Paul, and which supposed that this was a
good opportunity to diminish his influence, and to strengthen their
own cause. He was not now at large so as to be able: to meet and
confute them. They had access to the mass of the people. It was easy,
under plausible pretences, to insinuate hints about the ambitious
aims, or improper influence of Paul, or to take strong ground against
him and in favor of their own views, and they availed themselves of
this opportunity.
It is certainly possible that of these preachers of envy were envious of Paul and aghast at the loss of the Levitical law; but I believe that the story was more than this. The Cambridge commentary correctly observes:
Not that the Judaizer of the Pharisaic type was his only adversary
within the Church. He had also, very probably, to face an opposition
of a “libertine” type, a distortion of his own doctrine of free grace
(Romans 6:1, &c., and below, Php 3:18-19); and again an opposition of
the mystic, or gnostic, type, in which Jewish elements of observance
were bent with an alien theosophy and angelology (see the Ep. to the
Colossians). But ch. Php 3:1-9 fixes the reference here to Christians
of the type of Acts 15:1.