Consider the following scenario:

Create db.collection1 with UUID U1 at time T1.
Create db.collection2 with UUID U2 at time T2
Rename db.collection1 (U1) to db.collection2 (U2) with dropTarget: true at time T3
Drop db.collection2 (U1) at time T4

Now do an initial sync, starting the clone at some time after T4, but with the oplog replay start point of T2.

After the clone, no collections exist in db. After applying the entry at T2, db.collection2 (U2) exists. Applying the entry at T3 fails. The drop at T4 is for UUID U1, so it fails too. Now initial sync is done and a spurious collection2 exists. The rename should have dropped it, despite the source not existing.