repeated?: function [text][
    loop ((size text)/2)..0 'x [
        if prefix? text slice text x (size text)-1 [
            (x>0)? -> return slice text 0 x-1
                   -> return false
        ]
    ]
    return false
]

strings: {
    1001110011
    1110111011
    0010010010
    1010101010
    1111111111
    0100101101
    0100100
    101
    11
    00
    1
}

loop split.lines strings 'str [
    rep: repeated? str
    switch false = rep
        -> print [str "-> *not* a rep-string"]
        -> print [str "->" rep "( length:" size rep ")"]
]