you can [attach tags as many as possible](https://nextjs.org/docs/app/api-reference/functions/cacheTag#creating-tags-from-external-data) but you would only need one tag to revalidateTag

is there a difference between

cacheTag(["foo", "bar"])

and

cacheTag(["foo"])
cacheTag(["bar"])

or is it safe to call cacheTag multiple times? or will that have any problematic implications?

first of all - cacheTag has following signature: function cacheTag(...tags: string[]): void so passing array should result in type error. looking at implementation, cacheTag("foo", "bar") should work in same way ascacheTag("foo"); cacheTag("bar").

since revalidateTag accepts single tag and profile, you can do something like cacheTag("foo", "foo:" + some identifier). then calling revalidateTag("foo") should invalidate all resources that included "foo" in cache tags.