@Eliyahu ****
from what I have seen in past posts in Facebook, if you have already purchased a Tourist Visa before arriving in Thailand, when you arrive, the Immigration Officer will almost certainly stamp you in on that, even if your intention is to enter Visa Exempt. I would think that the only way to avoid that upon arrival, would be to tell the Immigration Officer BEFORE you hand over your Passport, tell them what your intentions are as you explained in your post and politely ask if they will allow you to enter on Visa Exempt this time.
If you don't have any bad history of entry stamps into the country that would concern Immigration, then I don't think it would be a problem whether you entered on the Visa on first entry and Visa Exempt after returning from the Philippines. Keep in mind, that entry, even with a Tourist Visa, can be refused if the Officer is concerned about any past history.