I don't know that there is any one specific fix to resolve this, at least not a simple one.
As a Calls volunteer, you are encouraged to upload all TGs captured by whatever tower, control channel, whatever you are monitoring and the system will filter out the stuff it needs to in a perfect world. Two of the three people who are providing Calls feeds I linked above are super inactive on the site, and not likely to respond. FrostTheFox is relatively active. Making sure all of them are keeping times as accurate as possible will help the site to know which calls are duplicates. The sites for surrounding counties could drop 12275 from their feeds. Not desirable from a personal standpoint if they are monitoring St Joseph as well personally. Broadcastify itself and the developer are aware that this can/is an issue and are working on some fixes, both to encourage providers to make sure their equipment and connection is up to date and to help the system be smarter about picking up these duplicates more accurately. There have been several posts over the last couple of years since Calls was launched.