Do you have default jetways showing at KDFW only, or everywhere ?
The GSX Control Panel surely must have fixed the double jetways on default airports but, at KDFW, we still haven't done a GSX profile with GSX/SODE jetways so, you are supposed to see custom FSDT jetways working with CTRL+J and nothing else, because GSX would add its own jetways automatically ONLY if a scenery uses the *default* jetway model, not a custom one. Those are never replaced automatically.
If you see the FSDT custom jetway and a GSX L2 jetway as well, it seems you made ( or downloaded ) a GSX profile for FSDT KDFW that adds GSX L2 jetways, but whoever made it, didn't include either the instructions to create an "Exclude" file, or they did, but you haven't followed them.
Normally, when you want to replace custom CTRL+J jetways on a 3rd party airport, you must follow the procedure explained at Page 61 of the GSX Manual, or in a video here: