Уважаемые форумчане.
Подскажите как убрать дубли страниц с сайта

На одном из сайтов прочёл что вставив этот код всё будет работать
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} ^(.+)/$
RewriteRule ^(.+)/$ /$1 [R=301,L]

Вставил на эффекта не произошло
Полная версия

# MODX supports Friendly URLs via this .htaccess file. You must serve web
# pages via Apache with mod_rewrite to use this functionality, and you must
# change the file name from ht.access to .htaccess.
#
# Make sure RewriteBase points to the directory where you installed MODX.
# E.g., "/modx" if your installation is in a "modx" subdirectory.
#
# You may choose to make your URLs non-case-sensitive by adding a NC directive
# to your rule: RewriteRule ^(.*)$ index.php?q=$1 [L,QSA,NC]

RewriteEngine On
RewriteBase /

RewriteCond %{HTTPS} !=on
RewriteRule ^(.*)$ https://название сайта/$1 [R=301,L]

# Rewrite www.domain.com -> domain.com -- used with SEO Strict URLs plugin
#RewriteCond %{HTTP_HOST} .
#RewriteCond %{HTTP_HOST} ^www.(.*)$ [NC]
#RewriteRule ^(.*)$ https://%1/$1 [R=301,L]
#
# or for the opposite domain.com -> www.domain.com use the following
# DO NOT USE BOTH
#
#RewriteCond %{HTTP_HOST} !^$
#RewriteCond %{HTTP_HOST} !^www\. [NC]
#RewriteCond %{HTTP_HOST} (.+)$
#RewriteRule ^(.*)$ https://www.%1/$1 [R=301,L] .



# Rewrite secure requests properly to prevent SSL cert warnings, e.g. prevent 
# https://www.domain.com when your cert only allows https://secure.domain.com
#RewriteCond %{SERVER_PORT} !^443
#RewriteRule (.*) https://example-domain-please-change.com/$1 [R=301,L]



# Redirect the manager to a specific domain - don't rename the ht.access file
# in the manager folder to use this this rule
#RewriteCond %{HTTP_HOST} !^example-domain-please-change\.com$ [NC]
#RewriteCond %{REQUEST_URI} ^/manager [NC]
#RewriteRule ^(.*)$ https://example-domain-please-change.com/$1 [R=301,L]

# Exclude /assets and /manager directories and images from rewrite rules
RewriteRule ^(manager|assets)/.*$ - [L]
RewriteRule \.(jpg|jpeg|png|gif|ico)$ - [L]


# The Friendly URLs part
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?q=$1 [L,QSA]
#Удаляю дубли /
RewriteCond %{REQUEST_URI} ^(.+)/$
RewriteRule ^(.+)/$ /$1 [R=301,L]



# Make sure .htc files are served with the proper MIME type, which is critical
# for XP SP2. Un-comment if your host allows htaccess MIME type overrides.

#AddType text/x-component .htc



# If your server is not already configured as such, the following directive
# should be uncommented in order to set PHP's register_globals option to OFF.
# This closes a major security hole that is abused by most XSS (cross-site
# scripting) attacks. For more information: http://php.net/register_globals
#
# To verify that this option has been set to OFF, open the Manager and choose
# Reports -> System Info and then click the phpinfo() link. Do a Find on Page
# for "register_globals". The Local Value should be OFF. If the Master Value
# is OFF then you do not need this directive here.
#
# IF REGISTER_GLOBALS DIRECTIVE CAUSES 500 INTERNAL SERVER ERRORS :
#
# Your server does not allow PHP directives to be set via .htaccess. In that
# case you must make this change in your php.ini file instead. If you are
# using a commercial web host, contact the administrators for assistance in
# doing this. Not all servers allow local php.ini files, and they should
# include all PHP configurations (not just this one), or you will effectively
# reset everything to PHP defaults. Consult www.php.net for more detailed
# information about setting PHP directives.

#php_flag register_globals Off



# For servers that support output compression, you should pick up a bit of
# speed by un-commenting the following lines.

#php_flag zlib.output_compression On
#php_value zlib.output_compression_level 5



# The following directives stop screen flicker in IE on CSS rollovers. If
# needed, un-comment the following rules. When they're in place, you may have
# to do a force-refresh in order to see changes in your designs.

#ExpiresActive On
#ExpiresByType image/gif A2592000
#ExpiresByType image/jpeg A2592000
#ExpiresByType image/png A2592000
#BrowserMatch "MSIE" brokenvary=1
#BrowserMatch "Mozilla/4.[0-9]{2}" brokenvary=1
#BrowserMatch "Opera" !brokenvary
#SetEnvIf brokenvary 1 force-no-vary

Подскажите где ошибся?