Seeing a second symbol allows some additional guessing. I agree with those who suggested this is a proprietary symbology. My guess is that it's based on Code 93. Both symbols follow a character structure of 3 bars and 3 spaces spanning 9 modules (plus a final bar to mark the stop character). Both symbols begin with a Code 93 start character and follow standard encoding up to a point (happens to be the 'D' in both). From there the next character is invalid as proper Code 93 but maybe marks the start of a numeric encoding that compacts 'n' digits (13 in these symbols) into fewer than 'n' symbols characters. The final 4 bars and 3 spaces are a custom stop character that makes the symbology unique yet readable with simple modifications to existing decoder software. I think the 13 digits after the 'D' might be encoded into 8 symbol characters, which would leave 2 symbol characters for check values similar to standard Code 93, but I haven't been able to work that out completely (yeah, this is a fun puzzle for me). All guesses, but reasonable guesses based on experience.
Not sure how helpful this is to the OP. A custom symbology probably means someone wanted to be the sole source of readers for a customer. Without that original reader, the obvious workarounds are build your own or use a different technology to read it, like OCR as someone suggested, or manual entry if it's just a small number of them.