You would normally change the raddle colour every 14 days, starting with a paler colour and then going darker.
If the tup mates more than the odd one for a second time, then you have a failing tup (he is firing blanks), or if it is the odd one or two, then something has gone wrong in the early stages or the ewe herself is infertile.
If this has only been the one to go for a second mating, I would suggest that there was an individual ewe problem, but it may be best to either remove the tup (so no odd lambing in June or later) or at least change the raddle colour and note down dates.