What? Tail number switches aircraft?

Can someone please explain this- I recently flew on Jet Blue N827JB and being the nerd I am have been tracking its travels ever since.


Yesterday, this plane went from FLL to BOS as an A320. It left BOS as an E190 to BWI, then BWI back to BOS as an E190 before it left BOS to TPA as an A320 again. How does this happen? I thought tail numbers were unique identifiers for a plane?

Looks like ratty data…