Re^2: Perl regular expression for amino acid sequence

Input 'xxxxxxxGNNNxxxxxxxNNNGYGYxxxxxxxGYGYNNNxxxxxxxNNNGNNNxxxxxxx' gives:

NNGYGY begins at position 19
GYGYNN begins at position 32
NNGN begins at position 47
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rather than

GNN begins at position 7       <---
NNGYGY begins at position 19
GYGYNN begins at position 32
NNGNN begins at position 47    <---
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