Don't worry, Theon and Aere are definitely staying out of it. They won't even go near a data bug or any indication of it. They won't say why, but Theon's attitude is generally ominous about the possible results.
As far as encountering players goes, they might do some trading, though they don't need to often, since they're very efficient at dungeoning, even just the two of them, so they've usually got the best equipment for their current level.
As far as previous incarnations go... lack of an IP address prevents anyone from discovering if they've accessed The World before or even where they're accessing it from. The oddest part is that neither of them have gone offline since they got online, even though at least a week has passed (which can be a long time in MMO). They're still at level 10, however, chatting with random passerby and generally wandering about the delta server more than they dungeon.
Why do I have the sudden image of Piros attempting to decipher Aere's speech, failing ridiculously of course, but thinking he has it and leading the two off on a wild goose chase because he thinks she knows where something is and won't tell him straight?
That could actually be quite funny...