Yes, I have seen Philippines used for a number of movies set in S.E Asian countries.
Interestingly I met a young guy in the bar a few months ago who was staring in a Banged Up Abroad TV doc that was supposedly set in Thailand, He said Thailand would not let them film it there so they came to Cambodia. He told me they made a mock up of a cell in an upstairs room in one of the shop/houses here.
He was an ex Scots Guard about 38 so if anyone sees the Docu, let me know