Version: vanilla-hammers-3.2.0-1.18.1.jar
Fabric: 0.13.2

Configuration:
Set Diamond Hammer Digging Speed to 0.86
Set Stone Hammer Digging Speed to 0.43

Steps:
Mine blocks with each hammer paying close attention to the time required.

Expected Result: Diamond hammer should mine twice as fast as Stone Hammer.
Actual Result: Stone hammer and Diamond hammer mine at the same speed.