cad automatically copies and renames block, why?

[Troy]

Hello

using mechanical 2000 w/power pack

Cad is automatically coping and renaming blocks when I use power pack to
insert a top view of a socket head cap screw. Ex: Block name "317549
wearplate" when I place the top view of the screw over the clearance hole,
on the part I end up with a second block in the DWG database named "317549
wearplateQ5G7491" the original block in the dwg also becomes the new block.
If the screw is power erased and the dwg purged the new block "317549
wearplateQ5G7491 is removed.

Why does it does this??

Thanks
Troy