My usage flow on the fediverse: encounter someone on Friendica, follow them, copy their address, paste it in Pleroma, follow them there, continue reading on Friendica, encounter a poll (not yet supported by Friendica), copy its address to Pleroma, vote there, see a notification in Pleroma that someone's account has migrated, which Friendica doesn't support, copy their address into Friendica, follow them there.

That's why you usually get two follows from me and why locked accounts see an extra request from me a few days after they migrated.