You better check every time you talk about chemicals. Having common parts in names does not mean anything. Furthermore, the "old" trivial names are very misleading. The "Alum" part in "Potassium Alum" comes from aluminium, so the name is somewhat rational; but "Chrome Alum" is a similar compound with chromium instead of aluminium, so it should be named "Potassium Chroum" or something like that with the same logic . But instead, it has the "alum" even when it does not contain aluminium!

Long story short, every time check what's the real chemical behind the name. There may be a difference in just one letter (a common example is sulfite vs. sulfate). This time we are lucky because although the names are misleading, they are not unambiguous, which is the case sometimes. They just need to be considered as "tags" instead of descriptions of these chemicals.

This is a bit sad part of chemistry, but no can do; it's the burden of the history. In the same way, the "unimportant" cation has given name to many compounds such as soda, potash etc.