I should have been migrated from my old ISP to Sky on the 12th but my old router is still happily connected though I think the speed has dropped. When I swap the routers, the Sky router can't connect.

The BT order tracking thing has these two entries...
PROVIDE LLU LINE SHARE PSTN Completed 12/10/06
CEASE BT IPSTREAM MAX Due 17/10/06

We're now between those dates and I notice that my old router is showing a Downstream noise margin of 2, it used to be somewhere in the mid teens.

From that evidence is it possible that both DSL connections are active on my line?