[mythtv-users] Duplicate channels

[Jeffrey Ratcliffe]

My UK-based mythtv setup has been working well, and I don't want to do
any major surgery to it, but over Christmas, I have had a few
duplicate recordings from the same channel at the same time (in this
case from ITV - I assume that different regions have different EPGs
with different programme names). Digging out some SQL, I see that I
have duplicate channels (several more than the excerpt below):

chanid  channum name    serviceid
12301   101     BBC One W Mid   10301
8940    102     BBC Two HD      6940
57411   102     BBC Two HD      6940
12060   103     ITV     10060
12080   103     ITV     10080

For the ~15 ITV examples, I can pull them apart from the serviceid.
For the others, it looks like the chanid.

Before I spend the time to do this, I would like to understand what
has happened.

Are these just regional channels, poorly named?

Why does Myth not complain about non-unique channum entries?

How does Myth decide which channel to take when there are non-unique
channum entries?

What SQL would pick out non-unique channum entries?

What do the duplicate serviceid entries mean? Multiple scans?

I'd be grateful for any insight.

Regards

Jeff