Duplicate calls on itemised bill

[#1]

I just noticed that the same call appears twice in the attached screenshot from my itemised bill web page. It's not a problem for me because I'm on Talk Anytime but I'm puzzled how this could happen and wonder if the same thing might be happening for users with chargeable calls

[#2]

Hi there,
Ben's had a look into this one.  It appears to be a one off display issue - we wouldn't have charged you the second call if the call wasn't included.
I'll keep an eye out for any further examples but I'm hoping it's just a one off.

[#3]

I've found another example with a chargeable call and traced the issue to some wonky grouping when a call spans 2 chargeable periods (e.g. daytime > evening). The customer has not been double charged.
I'm fairly sure I know the code change which caused this and it was solely an adjustment to the display of itemised bills, not creation of payments at the end of the month. I am very confident that we are not over/under charging customers.
I have raised this as a P2 - ref 75715
Cheers