They can be but their profiles don't look like alt accounts. @BlokchainB signed up a lot earlier than @frostdragon for example. They also seem to post at different times. @frostdragon was even gone for a while.^[1]

It's good to be vigilant in this stuff ("sat farmers") as @siggy47 mentioned here but I don't think it applies here.

1. Or at least they put in a ton of effort to maintain two alt accounts that look different. It's hard to proof this stuff without ID verification but we certainly don't want to go there ↩