Steps to reproduce:

1. Attach an Inventory Connector to a multiblock CFB fridge (formed with two singleblock fridges, and this should be the cause of the problem, maybe the connector treats it as two individual inventories. Singleblock ones work just fine)
2. Attach a terminal to the connector. (Directly attaching the terminal to the fridge causes no problem, I was doing this cuz I want more fridges in the network)
3. Insert something into the fridge.
4. Check the terminal. Items are visually doubled. You can still extract the exact amount of items you've filled in though.

I have seen the same behaviour when using Druidcraft crates, a multiblock storage solution that can be 1 block, 2 blocks, 4 blocks (in a 2x2), or 8 blocks (in a 2x2x2). My crafting terminal showed the number of items as a multiple of how many crates I had placed in the connected storage (so 1 stack of cobble showed as 64*8=512 items).

However, this only happened when the Inventory Connector was placed directly adjacent to the multiblock storage(s). If the crates were connected to the storage network by an Inventory Cable Connector, everything worked fine.

Should be fixed in 1.18 and 1.19 versions