Matching crown molding for built-in bookcase renovation

Hi, I’m well into the process of having built-in bookcases designed for my Prospect Heights co-op. The idea is to have the bookcases extend to the ceiling and have the existing molding continue around the built-ins to make them look like part of the original room. The problem is that the builder has only been able to approximate, not exactly match, the molding. I’m worried that this will look sloppy at the intersection of the two pieces. He’s essentially recreating my original molding using three pieces of Dykes molding, but again, it isn’t exact. What are the best ways to find matches for original molding? My existing molding can’t be that old, and I want to believe an exact match exists out there somewhere. I want to make sure I’ve exhausted all options before going with the imperfect version. Or am I being fussy about this and is it a compromise people deal with all of the time?

Many thanks in advance for any responses.

rw