I believe I was using Google to log in (I did recently lose a heap of passwords) and I do have another Google account attached to firstname.lastname@example.org
The only other email an account might be linked to is email@example.com which is the old work email. When I login in to Google using firstname.lastname@example.org and then go to Feed Burner it welcomes me as s.<email@example.com.> Incidentally all of my Feedburner feeds are missing too - though I can see they are still working and active for subscribers. Panic.
I used to have another Google account attached to firstname.lastname@example.org but I deleted that one months ago.
Does this help? I don't have any usernames except for creativelearningscot but that seems to have wandered off (I think it still exists in YouTube world).
If your question was asking specifically about the Pipes IDs, I had 14 pipes I think
I have had to give up on this one - effectively losing my entire list of subscribers and starting afresh. Even though the pipes I created are still running (14 of them) I can't edit or access any of them.
Using the one direct URL I had bookmarked I managed to click the 'clone' button and the clone appeared in my account! Totally bizarre. The clone meant I didn't have a to build the pipe from scratch but is so frustrating that the original pipes are somehow linked and yet not linked to my account.
Google have made a complete hash of buying up the range of sites and merging my accounts - I have lost 4 years of Google analytics, 14 sets of pipes and all of my feedburner feeds and even YouTube and Google and Yahoo identify me as 3 different names even though I'm logged in once with my google account. Crazy mess.