Open this directory "garrysmod/gamemodes/sandbox/gamemode/spawnmenu/creationmenu/content/contenttypes"
and look for a file called "dupes.lua"
Open this file and look for a function called 'function ws_dupe:DownloadAndArm( id )'
Modify the code to look like the following
Lua Code:
function ws_dupe:DownloadAndArm( id )
chat.AddText(Color(255,0,0), "Spawning dupes from the workshop has been disabled. You can still spawn your own saved dupes")
--MsgN( "Downloading Dupe...\n" )
--steamworks.Download( id, true, function( name )
--MsgN( "Finished - arming!\n" )
--ws_dupe:Arm( name );
--end )
end
For the chat.AddText, you can change the color and the text to what you want.
The '--' infront of the lines are comments. Just incase you want to re-enable the workshop dupes in the future just remove the '--'.
When someone tries to download a dupe from the workshop, it will just display the message.