Actually we have our precedent and it is given by the Lord through the very same prophet and in the very same Chapter you refer to, the 12th Chapter of Daniel.
Here the prophet Daniel was asking one of the two angels concerning the length of time until the fulfillment of the things spoken of in Verse 4 (specifically “the time of the end”), and the angel answered him in Verse 7 saying, “it shall be for a time, times, and half a time; and when the power of the holy people has been completely shattered, all these things shall be finished.”
“A time, times, and half a time,” or 3 1/2 times
Here you have your two numbers viz. the “times” plural, which have to be summed together.
In other words, 1 time (360) + 2 times (720) + 1/2 time (180) = 3 1/2 times (1260)
3 1/2 x 360 (the number of days in a lunar year) = 1,260 prophetic days, which are translated into 1,260 years, the period of Papacy’s rule from the setting up of the Abomination of Desolation in A.D. 539 to the “Time of the End” in A.D. 1799.