Zend certified PHP/Magento developer

Stream to multiple RTSP from one or more video files

I am not an expert on FFMPEG, I simply found this tool useful for doing some simple things I need to test on clients using RTSP streaming.
What I would like to do is to be able to RTSP stream the same video on two separated streams but synchronised.
Currently what I’ve managed to do is launch two sessions of the same video but when I request them together, they are never synchronised as they are requested at different times.
I’m using mediamtx as Media server and the FFMPEG command I use is the following one:

ffmpeg -re -stream_loop -1 -i NameFile.mkv -c copy -f rtsp rtsp://localhost:554/mystream1

I want to obtain two RTSP streams with one command, for example /mystream1 is the first one and /mystream2 is the 2nd one, maybe with a scale to have a lower quality) but the video input is the same (or I can already lower the res in input so I will use two separated videos).
I found something on google that could help me but unfortunately they were not what I was looking for. Mostly it was about mapping videos onto a single video but that’s not what I want to do.