In very specific circumstances, some users may want to run 2 or more instances of the StackAndTile program. Some reasons for this would be to have two separate stacks+grids for separate sites. Or perhaps a user wants to put all cash tables in one layout and all tournament tables in another. Or whatever other reason they could come up with.
It will require a little bit of work. First, realize that each instance of SaT will need to be running its own completely different layout file. So, you would start by simply opening SaT once. Then while its still open, just open it again. You should have two SaT windows.
Now on the 2nd window, you will need to use menu item "File -> New Layout" and create an entirely new layout. The important thing is that you will not want any of the slots to overlap with the other layout. So you may need to remove slots from both layouts, and reposition them using Visualize Grid so that they don't overlap. Remember, each instance of SaT will only handle the detection for the specific sites included in that layout. You need to make sure not to include the same site in both instances.
Next you will probably want to set up the exact same hotkeys that you have in the other instance. But, the difference is that you should use the ~ character as a prefix at the start of the keyname. So, if you wanted to use the F1 key as a hotkey, you would need to make sure to put ~F1. You can just type this character in the hotkey box
And the next time you start your session, you would just use File -> Open Layout to make sure that each instance is running separate layouts.
Here are some forum links where people have asked about it:
https://www.stackandtile.com/forum/showthread.php?tid=743
https://www.stackandtile.com/forum/showthread.php?tid=816
https://www.stackandtile.com/forum/showthread.php?tid=925