Copper chests become double-chests even if their oxidation doesn't match

It is possible to create a double-chest by combining any two types of copper chest regardless of whether their oxidation levels match. When two copper chests with differing levels of “oxidation” are combined, the double-chest defaults to the “youngest” age (i.e. when an oxidized copper chest is placed adjacent to a copper chest, a double-chest is created and the oxidized chest loses its oxidation).

This issue can be easily replicated with any copper chest type: first place a copper chest, then place another copper chest with any amount of aging adjacent to the first copper chest; a double-chest will be created, and the copper chest with more oxidation will match the chest with less oxidation.

Expected result: placing a copper chest next to another copper chest should only create a double-chest if they are the same type (if the levels of oxidation match).

Actual result: a double-copper chest can be created with any two types of copper chest, regardless of whether the level of oxidation is the same or different between them.