For a long while, the Philippine government didn't allow you to hold a philippine passport if you got one from another country (heralding the good old crab mentality again - how dare you try for a life in another country, and if you do, we don't want you in the Philippines).
However, within the past 12 months, in a surprisingly unusual fit of common sense, Gloria changed the rule to allow filipinos to hold dual citizenship. Presumably because she realised that all those OFWs and whatever who got a second citizenship and were faced with the ridiculous philippine ultimatum of one passport or the other were telling the philippines where they could shove it and she didn't want to lose out on all that life saving lovely remittance income which is propping the country up.
For my daughter, we got passports at the same time and, being the Philippines, their "robust and detailed governance checks" (ho ho) did not spot she was already a british citizen. There is, I think, a form to fill in from (I guess) the Bureau of Immigration which will now allow any filipino/a to hold dual citizenship and either regain, or not lose, philippine citizenship (and thus legally hold two passports).
Although, to be honest, I would always choose the UK passport to travel on - lessens the possibilities for any immigration twonk to make exiting the country difficult. Seeing as the philippine embassy dishes out 6 month visas to anyone, provided they can stand upright, I would probably go for that option if I wanted to stay longer, then you have the added assurance of travelling "at her majesty's pleasure", and no-one at the airport can challenge your right to return to the UK (or anywhere).
