A bilateral mistake of fact occurs when both parties to a contract are mistaken about a material fact. A bilateral mistake of law occurs when both parties are mistaken about the legal implications of the contract terms. In both cases, the mistake must be mutual and fundamental to the contract in order to potentially invalidate it.

An error made by 2 parties, who believe differently and/or incorrectly about the facts in the contract.

bilateral or mutual mistake; a material fact that is mistaken by both parties. In such a case, the party who is adversely affected by the mistake has the right to cancel or rescind the contract. Sometimes a word or term is materially interpreted differently by each party, their mutual misunderstanding may allow the contract to be rescinded.

A leech has a bilateral simmetry.

Bilateral legs

They have bilateral symmetry. Though they are round they don't have radial symmetry