You are given a string which contains more than $10$ characters and is compose of a series of $$A$,$B$,$C$$ and $$D$.$ Write a programme in python which returns all the $10-$letter$-$long substrings that occur more than once in the given string. For example, for an input of "AAAAACCCCCAAAAACCCCCCAAAAABBBDDD", the output should be $[$AAAAACCCCC$,$CCCCCAAAAA$].$ For an input of $$AAAAAAAAAAAAA$,$ the output should be $["$AAAAAAAAAA$"]$