Service tax under reverse charge - gta

Hello,

What if a Goods Transport Agency deposits the service tax even in cases where the liability to pay service tax was on receiver of the services

e.g. ABC PVT. LTD. wants to send the goods to PQR LTD. For that ABC contacts XYZ which is a GTA

Now lets assume the liability to pay freight was on ABC Pvt. Ltd. & so ABC is the person liable to pay tax.

But what would happen if instead of ABC XYZ(GTA) deposits the service tax

1.) Can Deptt. demand service tax from ABC also?

2.) If yes then wont it be a case of double taxation? Also can XYZ take the refund of tax deposited by itself if deptt. insists on ABC to pay Service Tax.

Please help me with this query

-Thanks