TLDR: They're probably not bots, but they do have some similarities and exhibit some traits that might seem a bit suspicious.
They have some big differences in their stats, so they're definitely not using a program that outputs the same or similar strategy like you'll see with the lower stakes bots.
They both incorporate a short-stacking strategy where they'll often buy-in for the minimum. This is not that unusual by itself, but it isn't that common to see from most regs playing at these stakes on this network.
I've also never identified a fully autonomous short-stacking bot.
ytrewq doesn't seem to like me for one reason or another. He's constantly talking trash to me at the tables. I can count on one hand how many suspected bots I've seen chat at all.
For these reasons I don't believe they're likely to be bots. I'm not saying it's impossible for them both to be using something, I just think it's less likely then you assumed.
They are both from the same city of Minsk.
They won't play each other HU, but they are very adamant that you play them 3-handed when you sit at a table with both of them. ytrewq will go from sitting out to instantly sitting in and talking trash to me if I don't sit in too.
I'm not sure where some of these players got the idea that it's OK to sit out HU, but not OK to sit out when there's 3 players at a table. I've seen other players than just these two say that. That's not something that is mentioned on the rules page.
I rarely ever table camp, but camping is not explicitly stated in the rules. Most often if you see me sitting out it's either because I'm taking a brief bathroom break, I got disconnected or I'm having a brief chat with someone at a short-handed table. I don't call other people out for table camping.
Table blocking is mentioned in the rules. My interpretation of table blocking, whether correctly or incorrectly interpreted, is that you shouldn't be sitting at a full table just because another player at that table has sat out while simultaneously playing on other tables for more than your current orbit. You should either be sitting out at all tables for a brief break every once in a while or leaving the one you're sitting out at if you'd like to continue playing at the others. I regularly call people out for abusing this rule.
Since they're from the same city and both use a short-stacking strategy it's possible that they have a connection off of the tables, but I have no proof of that. Add the fact that they won't play each other HU, but they're adamant that you play them 3-handed and it's a little suspicious.
I can't definitively say whether there's any collusion or soft-playing going on between them. I don't believe my database has a feature where I could check such things like how many big pots they've played vs each other or how often they 3-bet/4-bet/raise each other vs how often they do that against the general population. I think there are databases with graphs that can show you that kind of stuff.
ytrewq plays a lot more 500NL and some 1KNL while S1000RR plays 1KNL and 2KNL more often than ytrewq does. It doesn't appear that they always play together or sit at the same tables. When they do, it appears to be mostly at 1KNL.
Let me know if you come across anything else suspicious about them, but at the moment I have no proof of any impropriety after taking a brief look at them.