You are obviously installing all instances in the same folder and trying to run them from there.
The Time Machine database is stored in the same place, so when you are trying to access it using several instances at the same time, of course it gives you an error and crashes.
To resolve this problem, you must copy the Time Machine database in a separate folder for each instance you are running and specify that path in each settings profile you are using.
So go to this folder:
1. c:\Users\%username%\MarketFeeder Pro 8\timemachine\
2. Create a folder elsewhere, for example, c:\Users\%username%\MarketFeeder Pro 8\timemachine2.
3. Copy (not move!) tm.db from timemachine to timemachine2.
4. Start one of the instances of MF Pro. Open Settings and switch to the Time Machine tab. Enter the path "c:\Users\%username%\MarketFeeder Pro 8\timemachine2" into the text field titled "Path to the folder where the database file is stored".
5. Save the Settings and restart that instance.
Here is what the Time Machine manual says about this option:
You can optionally store your Time Machine database file in a customized directory. This file can quickly inflate to tens of gigabytes, so you might want to specify a designated location for its storage (maybe even on an external medium). Specify the path to a custom folder where you want to store the file. Please note you will have to stop MF Pro, manually copy your database to that folder and then restart the program. You will see the instructions on the screen once you have chosen the new folder path.
It is very important to make sure that you have system a permission to write into that folder (either set that permission yourself or ask your system administrator to do so).
Repeat these steps with each instance you intend to use. Make sure each settings profile links to a different path!
Mind you, the database file is huge, so you might want to check if there is enough disk space to store all its copies. Also, keep in mind that if you download some markets into one of the instances, you will need to copy the updated tm.db file to all other destinations for the new markets to appear in those copies.