Issue description:
A crash (It says with Greg's Construct)
If crashed, link to crash report (use a site such as pastebin):
https://paste.dimdev.org/bakuyubuda.mccrash
Versions:

• Minecraft: 1.12.2
• Forge: 1.12.2 - 14.23.5.2847
• Mantle: 1.12-1.3.3.55
• Tinkers Construct: 1.12.2-2.13.0.171

Can it be reproduced with just Tinkers Construct? If not, list the other mods required to reproduce the issue.
This is the original Greg's Construct (the link above was supposed to be a "fixed" fork)

Greg's Construct bug, they are registering a duplicate material to another mod (Armory Expansion - MatterOverdrive). We leave it to addons to decide how to resolve conflicts as there is no good solution.