1. Yes, this agreement shall be deemed concluded.
2. If the second copy is not signed, the contract will still be deemed to be concluded. The law does not oblige to do the n-Noe number of copies of the document. Another thing is that without the original in case of dispute one of the parties can be a problem.
3. Stitching and signature on each page is not a guarantee. Stitching can be easily removed and glued again able people, and forged signatures. Once found in the court amended page of the contract where the penalty prescribed by me, was removed, and the bottom tried to get my signature.
Conclusions: if you want to deceive -- deceive. To have at least some protection, keep the evidence, which version exactly did you coordinate with the other party. A draft of the contract to which both parties had agreed. Correspondence, to discuss controversial points. It somehow helps to build a position in the court.