Unable to delete duplicated assets with 'old' name

Unable to delete duplicated assets with 'old' name

Hi All,
 
Our license for maximum assets recently hit its limit. I noticed immediately that quite a large number of machines had duplicated themselves to old_1, 2, 3, 4, sometimes even to 20.
 
I've tried to delete these assets, but the browser window times out after 30 minutes.
 
I tried deleting one only, and this took a total of 20 minutes to delete one workstation.
 
Im not too sure how long these workstations have been there for. Is there any way I can remove these workstations and stop future scans from doing the same thing?
 
SDPlus version 9012.

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