I will first state the dictionary entry, and then other formations that also yield the dictionary entry.
Consider the following :
思える - to seem/appear,
- potential form of 思う - can think
合わせる - to join together,
potential form of 合わす - can join together
causative form of 合う - to let suit/match/agree with
解ける - to come untied / be solved
- potential form of 解く - can untie/solve
空ける - to empty
- potential form of 空く - can become empty
As above, there are words that in their potential/causative form that already have a dictionary meaning that is different from their conjugated forms.
(Question) Were they equal in meaning at some point in time? Or are they completely different words and should be treated as such?