SEO page title can't seem to be changed on duplicate pages?

Site URL: http://www.marleyshouseofsport.com

I've been duplicating pages on my website to make building things a bit easier but notice that in the options under SEO there's not an option to change the SEO site title on my duplicate pages. Now this granted is in my members only section (which is not live yet because I'm still deciding on whether to pay for it and have one or not...) but I'm not sure if this is the reason I can't change it. Does anyone have any input on this.

It's not really relevant to this post since you can't see the pages on the site in question but just in case the access password is:  accessgranted77

Hi. Have you tried contacting Squarespace Customer Care to ask this? They can check backend to troubleshoot the cause.