Contents of $c were found as expected. But, take a look at this (grep output):

   charangaBoomBANG!
   D-charangaBoomBANG!
   D-xxxxxxxxBoomBANG!
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It looks like substr() operation duped $d string and served me another instance with copy of my old data.

That was my second try after assigning an empty string '' gave similar result (preserved secret "D-...BANG!")

My all hopes are now towards vec() function and I'll give it a try right away!

Cherio!