Modpack version
1.74

Issue
Duplicate blocks using a chisel from tinkers construct.
Step 1: Put any block that is possible to chisel in a chisel from tinkers construct.
Step 2: Wear down the duribility of the chisel.
Step 3: Break the chisel with blocks still inside and the chisel will drop the remaining blocks.
Step 4: Repair the chisel and the blocks will still be inside.

This has been reported oops