domain alias in WordPress

We have a WordPress website for which we have setup alias in Hostgator (where the website is hosted). The actual website is schibstedpanelen.se and we have setup alias as backend.schibstedpanelen.se. And when we load backend.schibstedpanelen.se it redirects to schibstedpanelen.se whereas we want it to display content of schibstedpanelen.se but the domain should remain same i.e. backend.schibstedpanelen.se should not redirect to schibstedpanelen.se. Is there any default setting in WordPress which is making this to happen? Because we tried to setup alias for non WordPress and it worked for us. Could anyone help with this

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