The Copper Golem shouldn't sort differently named items together.

When building an Item Sorter of some kind, "Filler Items" have always been used to prevent unwanted items from being sorted into the wrong chest. To facilitate this, Filler Items need to be something that would never naturally find its way into the sorting system. Usually this means a renamed common item, such as renaming a piece of cobblestone "FILLER".

Filler items also have their place in the systems that can be made with the new Copper Golems, but not if they sort renamed items together with their unnamed counterparts. It will be so much more of a hassle to build a larger sorting system with Copper Golems if they keep doing so.

And before anyone suggests using some specific item as the filler, and just not putting that item in the sorter otherwise, the problem with that is that you'd require a very rare item to use as filler for that to work, and grinding for multiple stacks of, say, Netherstars, or Hearts of the Sea, is just not an attractive alternative.

In summary: Please don't make Copper Golem sort differently named items together. If the player decided to rename a common item, he likely meant for it to be separate from its unnamed counterparts anyway.