On re-reading your question, maybe I misunderstood. You probably are not asking if you can double the dose, but whether it would be OK to take 2 g of one and then 2 g of the other. Is that right? That would be fine, since they are the same drug.
Welcome to the STD forum. Oral herpes isn't an STD, I'm but happy to answer. (In the future, you can use the MedHelp herpes forum.)
1) Valacyclovir and Valtrex are identical: Valtrex is the dominant brand name, valacylcovir the generic name. Do not take both; it would be an overdose. (Probably not harmful, but not recommended.) You get maximum effectiveness against oral herpes with the 2 g (2000 mg) dose taken twice a day apart; higher, more frequent, or more prolonged treatment will make no difference.
2) You are typical in not having an identifed trigger of your outbreaks. Most people cannot pinpoint particular events. As for the continuing severity and frequency, that also is typical. Over the long run, the frequency might decline -- but for the first few years, most people have a steady rate of outbreaks. However, I'm not an expert in oral herpes; Terri Warren, moderator of the herpes forum, might have further thoughts about this.
Best wishes-- HHH, MD