I have not experienced that myself, and I don't know of any reason why that might occur (but my knowledge of how TV Server works is not extensive).There were two stations that had multiple copies of the channel, and when I deleted one, it deleted all of the other copies of the channel, too.
It is strange that you mention this because there are now four DVB-T channels in the UK that behave in the same way (this is new for the UK). I think that these might be some sort of placeholder channels that don't have a full set of the various ids that define a channel. Regardless, they appear after each scan and have to be deleted manually (otherwise the copies accumulate).The only "issue" that I see remaining is that if I repeat a channel scan, some channels - apparently the same channels each time - get duplicated necessitating a manual deletion of these duplicated channels.
I am glad that you were able to clean-up your channel list.
-- from CyberSimian in the UK