Take any pair of numbers, say 9 and 14.
Take the larger number, 14, and count up by that amount :
Then divide each of the values by 9, your chosen smaller number, and look at the remainders.
Now do the same again but using different numbers, say 7 and 12.
Counting in twelves and dividing each result by 7 :
Pick the pairs how you like, somewhere there'll always be a one - won't there?
What actually happens?