Old Topic, May be things have changed a bit now.
http://182.180.158.25/multiplestbgpon.html - seems official version on 3 TV screens with 3 STBs @ Rs 200 per addl screen.
This is however, applicable on GPON connections only.
A work Around (not fully tested though):
The recent topbox of PTCL is android working both on wifi as well as Ethernet. Tested and found that it does not need to be connected to the PTCL router using Ethernet, connects through wifi with router while can be connected to TV using HDMI etc.
So if you have above 4 mbs connection (free smart tv), 2 STBs, one working with wifi other through ethernet, I don't find a way that PTCL should know if the second one a smart tv app, working with addl tv or smart tv app working on andriod phone.