Meter Readings

We have a meter with two readings (one lower, one higher) and I assumed we were on a dual rate (economy 7)
However, our bills are always charged with the readings at the same rate which would imply we are not on an economy 7 meter.
I wondered whether perhaps we have two supplies? The property was originally split into a main house and a separate flat, I believe, and there are two active fuse boxes in the property, so this does seem possible?
Any advice on how I can find out much appreciated as our bills seem rather high for electricity.