It depends what you mean by similar. "Similar" to someone with limited experience could result in wildly different groups being lumped together by mistake.
Inocybe geophylla var lilacina has been mistaken for
Laccaria amethystina by people with limited knowledge of fungi. This is poisonous and you would not want to eat it. But to someone with a reasonable amount of experience they are not similar at all.
If you are only 95% certain (or even 99% certain) that means you have some doubt. If you have any doubt at all you should not eat a mushroom. With fungi, the risk is that your one mistake could be your last mistake.
Ken