Cannot add duplicate collection entry of type 'add' with unique key attribute 'name' set to 'SiteMap'

[skypean]

I tried to install C1 CMS version 6.10 for some researches, but got the following error. I could not figure out how could I fix it, as I did not find any duplicate of SiteMap entry with applicationhost.config and web.config file.

I tried to add <remove name="SiteMap" />, then it works for SiteMap, but the same error occurs again with UrlRoutingHandler. I follow up to add <remove name="UrlRoutingHandler" />, but it doesn't work anymore. How would I fix it?