Attaching a lead to a mob (cow) in the nether and walking it through a nether portal results in a duplication of the lead after it detaches from the mob after the mob has passed through the portal.
MC-70923
Lead Duplication
Resolved
Duplicate
0
M.P. McDonald
(Unassigned)
Unconfirmed
Minecraft 1.8
Retrieved
This bug was also reported on my server today.