Graham Waplocus that is the code headtags cannot be turned off like header and footer
all you have to do is change the examples in
# Alt headtags pages data variable
var $alt_headtags_pages = {{:
folder/page|
folder/|
sub.domain.com|
domain.com/sub|
test=1|
:}}
to the file querystring folder or subdomains on your site that you want to turn off headtags
copy your normal tags to
# Output the normal headtags and exit
print {{ Normal Headtags }}
and either leave it blank or set alternative tags in
# Output the alternative headtags and exit
print {{ Alternative Headtags }}
And then copy the code to your _headtags file

if you take out all the remarks and empty lines it's quite a short code