DVB-T Freeview - repeated channels, which frequency?

[Mud]

I've just got a new aerial and amplifier in order to sort out a few niggles and now I'm confronted by twice as many channels to choose from. Is it a case of the different frequencies carrying exactly the same signal, or is there any difference/benefit to choosing higher frequencies? Vista's Media Centre seems to have chosen mostly low frequency channels (I'm under Mendip and live 1/2 way down a sort of mini-valley).

I've searched about, but can't find an answer.

 

[Mud]

St George. Knowing that Mendip is 716MHz+ I can manually prune in 'edit channels'

I don't think I can pull/plug-in the aerial mid-scan as Media Centre only gives you a % and not the frequency sweep information.

Can you point me at (or give me a brand name of) a filter? These're news to me and I'd like to look them up.

 

[Mud]

Thanks Tesla, I'll gladly take the file...I think I'll opt for the manual method for now, although I can see that starting to grate given Media Centre's tendency to occasionally lose the listings! I've not seen an option to manually add channels; you scan, it selects what it thinks is right (sometimes more, sometimes less), then you can add/remove the other possible channels it detected in the guide options.