When matching, use anchors in the regex to only match the whole word:

my $namecnt = qr/^(David|Tom|Sam|Will|Dave|William|Thomas)$/;
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^ matches at the beginning, $ matches at the end.

The match will now look like (I removed the /o as it's not recommended)

        if ($word =~ /$namecnt/i) {
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Note that the first argument to split is a regex. It's clearer to write

my @words = split /:/;
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