Also curious for an answer to this. DL did this on the intra-Asia flights back in the day. IIRC DL275 was on a 744 DTW-NRT and 'continuing on' a completely unrelated 763 NRT-MNL.
Tangentially related, WN does this all the time so they can claim to serve more destinations from cities and it drives me nuts. It is a connection by any other name- deplane, walk, get on a different plane. Arbitrarily the number is the same, so what?
Edit: 2 answers came in while I was typing this post.