If they match then the source code under escrow is authentic and complete. Neither of these procedures requires the intrusive participation of the escrow agent. The licensor and licensee are in the best position by far to conduct a verification test because it is a simple procedure and they know the products being inspected. A third party stranger would need to climb a steep product learning curve just to recognize what was being placed in front of him. There are other methods of verification but they are no more than a scam to tie needless and costly services into an escrow agreement.
Neutrality has no place in a legal brawl over ownership of intellectual property.
In a traditional software escrow, both the supplier and user have a legitimate interest in the source materials, and it is therefore necessary that a balance of those interests be struck in the escrow agreement, part of which involves custody by a neutral third party. But no such dynamic is at work in a copyright dispute, as the owner of the software has only one goal in mind - to lay a legal club across the skulls of infringers. Better still, get advice from your lawyer on the complete procedure.