From my perspective as someone who has worked in a commercial bakery and 2 decades with a catering company...
I cannot see any functional reason to connect two pot holders. The extra fabric would just get in the way. I can see it catching on handles (either cupboards or pots on the stove).
I prefer pot holders with heavy 100% cotton terry on the inside and on one of the outsides. The terry has great insulating properties and gives better grip. I have used old bath towels for the inside of pot holders and hot pads.
Use the extra yard of fabric to make a hot pad and trim a couple tea towels with it