Easiest is to run separate lines.
Tapping two condensate lines together into a common drain line is possible, but you have to make sure that each line is sized properly (3/4" pipe minimum up to 20 ton capacity), sloped properly (1/8" per ft minimum slope, although 1/4" per ft considered 'better'
AND
you have to have each drain line have it's own trap before they join at the wye.
btw, the overflow pan drain line has to be SEPARATE on the HVAC unit. And that drain line has to be located such that the user can see/tell if drainage is occurring there so that they can fix the clog in the main drain line.
And watch out if the drain lines run to the main house DWV system. Have to make SURE that venting and traps are 100% good in that case so that sewer gas doesn't get back into the house via the condensate drain line(s).
example:
https://inspectapedia.com/aircond/1633s.jpg