From the mailing list:
FileTxnSnapLog.restore contains a code block handling a NODEEXISTS failure during deserialization. The problem is explained there in a code comment. The code block however is only executed for a CREATE txn, not for a multiTxn containing a CREATE.
Even if the mentioned code block would also be executed for multi transactions, it needs adaption for multi transactions. What, if after the first failed transaction in a multi txn during deserialization, there would be subsequent transactions in the same multi that would also have failed?
We don't know, since the first failed transaction hides the information about the remaining transactions.