This could be because you have trailing spaces in your item IDs.
QuickBooks will remove the trailing space, while CW keeps it. So when we create it, QuickBooks changes it from "CCTV Level 2-Onsite | Maintenance " to "CCTV Level 2-Onsite | Maintenance".
When we look for "CCTV Level 2-Onsite | Maintenance " we don't find it, because only "CCTV Level 2-Onsite | Maintenance" exists, so we try to create it again.
"CCTV Level 2-Onsite | Maintenance "
"CCTV Level 2-Onsite | Maintenance"
"CCTV Level 2-Onsite | Maintenance"
ConnectWise PSA will treat those as two separate products (and let you have both), QuickBooks will delete the spaces from the end of the first one and treat them both as the same product.
Remove the trailing space and you will be set.