Is this a valid contract ?

[Scot22]

An agreement document was signed by one party.in City A. The other party in City B signed an additional signature page on a different day, not reading the full document. There had been 2 amended documents. Yes, careless should not have signed without reading.
Two questions. 1) If a document is not agreed and signed simultaneously by both parties is it still binding ?
2) It may be an earlier document was used instead of final agreement. If that is the case is the agreement still valid ?

[efpom]

On 1 - yes
On 2 - no

[Scot22]

Thanks. I always appreciate people giving their time to give their opinion.