basic gallery photo question

[PMah]

Sorry, I did some searching but I am perhaps overlooking topics that have been covered many times before:

Do Gallery photos have to be a single merged photo file with obverse and reverse in one image?  Is there a way to upload separate Obv and Rev photos?

Suspecting the answers are "Yes" and "No", does anyone know a super-quick shortcut for attaching side-by-side images for the Gallery?  I am using MS Paint 3D to combine pix and it just takes too .... long. 

All this by way of explaining that my last Gallery addition was in October 2019, and my backlog of Gallery-worthy coins was already substantial then. 

Please stay healthy!

[Pharsalos]

I join my photos online at: https://old.photojoiner.net

There are probably free Apps that do the same thing somewhere.

[v-drome]

Wow!  That website seems to work really well.  I have been arranging the photos on the desktop and using the "grab" application on my Imac, but for joining a simple obverse and reverse that is already cropped, this is much easier.  (I will still use the Preview app to adjust the size to 250-350KB before uploading them to Forum, but I can keep the high resolution composites on file, as well.) Thanks.