Your $time2 is only replacing the bits that "matched", the parts unmatched are not touched.

And also in your other attempt: 
$time2 =~ s/^(\d{2})(\d{2})(\d{2})\.(\d{2}).*?$/$1:$2:$3.$4/;
#                                             ^
#                                             add anchor point

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In reply to Re: A would-be simple substitution... by Roger
in thread A would-be simple substitution... by GaijinPunch

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