pt checksum differente number of chunks in the replica

Hello, i’m running pt checksum regularly and i noticed for some tables there is a different number of chunks in the master and in the replica.
I’m using --replicate heartbeat.checksums and i see in checksums a differet number of rows for some table, if i compare the crc column i don’t see any difference.
also pt-table-sync doesn’t show any difference.
can you explain ?
thank you