I don't know if they have to be different email addresses. I'm down to just two email accounts (MSN and a Gmail) but previously had four; one ended when I left the paper and another when my website went down.
If you only have one email, you can try using it for both. If that doesn't work, you can open another one, like Gmail, pretty quickly. That's handy if you don't want to use your main email for things like ordering online so you don't get flooded with ads.
Once upon a time in the early days of AOL, you could have multiple screen names/user names on one account; I guess maybe the assumption back then was that an entire family would use one PC. I had five user names in order to compartmentalize my online activity. One was made inactive--I forget why; it wasn't an action on my part. For a reason or reasons I can no longer remember--it was that long ago--I began using the same user name for both my leather club activity and for accessing Bettermost.
Right now my head is about to explode from everything I need to think about, decide, and can't keep track of. Maybe I'm just too physically exhausted this evening, but I can't deal with this--figuring what to set up and use where, if Facebook is even necessary any more for leather activities, how to make these decisions, whether I'm making the right decisions. ...
Ads have never particularly bothered me. I just ignore them.