template.properties
--------------------
stree.address=#enter address#
city.name=place
sate.name=unk


current.txt
--------------------
street.address=1234_ave_west
city.name=seattle
state.name=wa

####################CODE#############################
open (templateFile, "C:/template.properties") 
or die "Could not open file: $!";

open (currentValues, "C:/current.txt") 
or die "Could not open file: $!";

foreach $line (<currentValues>)
 {
	($k, $v) = split /=/, $line;
	foreach $tmpLine(<templateFile>) 
	{
		print $k;
		if (m/$k/) 
		{
			print $line;
		}
		else 
		{
			print $tmpLine;
		}
	}

}

close templateFile;
close currentValues;