The same widened block can mean two opposite things. Either the stays Lemon already tracks are still real and the OTA merged them (protect them), or those stays were cancelled and a new reservation now occupies the range (track the new one, release the old). The feed cannot say which.
Lemon's classifier prefers the explanation that requires fewer coincidences: explaining a block as a merge would require several brand-new, perfectly chained reservations to appear within one five-minute sync. When the block is classified as a supersede, it is consolidated into one pending_review booking under the real UID and the stale stays are allowed to cancel normally. When the classifier cannot decide, nothing automatic happens — the host is asked.