1. A one-sentence summary of bug: Heads obtained with the WilderBlade will only stack with heads obtained at that time. I have obtained cow heads several times, but they will not stack with each other.

2. Priority to fix? Medium

3. Which server? Cypress

4. Steps to Reproduce: Use WilderBlade on cow herd, get 2 or more heads named "cow head".  Put heads into chest.  Come back later and use WilderBlade on cow heard. Get 1 or more heads also named "cow head".  Heads will not stack with previous heads in chest or inventory. Happens with all other mob heads obtained so far.

5. Expected Outcome: Heads of the same mob type should stack.

6. Actual Outcome: Multiple stacks of the same mob head.

7. Proposed Fix (Optional): Let them stack.

8. Notes (Optional): Also noted that if I place a head down and then mine it, it gets a new name that is different.  "MHF_Cow's Head" instead of "cow head"

9. Screenshots (Preferred): Do you have screenshots of the problem, proof or reference?

Just to add information:
The non-stacking bit is due to the NBT data being different. I'm not sure what information we store, what gets stored naturally, and if we can adjust it. But if we can set all the NBT data to constants, that could potentially resolve the issue.

As for the Name changing, that's simply because any block that is placed and then broken will be dropped with their standard minecraft name. We could potentially adjust loot tables for it as a resolution.