Confirmed, but not as reported.
The first issue with this report is that nowhere does it tell me how to get the issue started. Simply equipping a spear and throwing it doesn't work. The second issue is that this issue DOES work on other spears. It's all about how the initial issue gets started.
Get several of all 3 spears
Equip a spear to the tool belt
Throw the spear into a wall or other block structure and see that everything is normal
LMB+drag the spear off the tool belt so that it's attached to the cursor
HOLD shift and then LMB click on another spear to move it to the tool belt
Click LMB on an empty slot to release the 1st spear back to inventory
Hit ESC to exit inventory
While standing close to a wall or other block structure, hold RMB to charge the throw
As soon as the spear is released, start spamming E to pick it up quickly
Observe the tooltip text on screen next to the crosshairs
Repeat for other spear types