Her passport expires in Dec 2019. Could this be a reason?

Sorry for confusing you, the visa vignette is valid only of 30 days from 15 May to 14 June 2017. The expiry date was mentioned in the visa letter and not in vignette. The visa letter States the following "you will have permission to be in the UK (known as Leave to Enter) as Tier 2 Partner from ...

Thank you cr001, by visa application center do yiu mean VFS in home country or is it ok to approach visa application center in UK?

CR001, Casa, iworker - please reply..

Hi,
I got Tier 2 visa on Feb 2017 which is valid till May 2020. But my wife's visa which is stamped May 2017 onwards and expires on Jul 2019. Why the difference in Dependant's end date? Is it an error? Anyone experienced same? Admins please advise what to do.

There is no need to get photocopy attested.

You can apply together.

If you are carrying both old and new Passports, then it's fine, make sure to keep both during visa doc submission, what matters more is whether you are a TB risk or not. In fact, during my visa doc submission at Vfs, they barely looked or opened the chest x-ray and returned to me there itself.

You should mention your wife's Passport number and yes it should be signed by the director.
To be safe, it's better to include tenancy agreement and landlord Noc along with the maintenance letter.