Fresh install of Jenkins
Create "new item", free style project. called TEST
Set "Advanced Project Options" and "use custom workspace" path.

Under "Source Code Management" Subversion.
Set the URL
Click "add more locations"
Set additional URL.

Start the TEST

After checking out the first location, the second checkout wipes out the first

So the checkout is left with only the second checkout. I didn't find a way to workaround this problem.