There is DTM being used on a site. Could Launch also be on the site at the same time? And would data collected from Launch go into a separate report suite?
No, you can't use DTM and Launch on the same page.
Both DTM and Launch use the global variable window._satellite. So, whichever library loaded last would overwrite the other and things would break.
You could do it, and data would g where you point it.
But not a great idea to put any two tag managers on the same page. It may interfere with each other and cause problems
Would it overwrite even if I use two different tracking variables?
As Ben mentioned both DTM and Launch use the _satellite object so the script that is loaded last will overwrite this object and thus also overwrite the settings like report suite.
If I use DTM to send data to report suite A and launch to send data to report suite B, how would it overwrite values if its sending data to two different report suites. would it still cause problem?