Yes, it can harm SEO not only SEO but the overall performance of your website on Google. As your website has already existed with different extensions Google can get easily confused by it and have a bad impact on your site. Also, customers get confused for the same reason and it can damage your website traffic and harm the site vary badly.

I don't understand your question.

xyza.com and xyzb.com are not the same.

Sorry for the Confusing Question and thanks for replying. So I have a website pacificmetalindia.com and there is one more website pacificmetal.co.in now because of that my website is not getting much traffic even though I am building backlink and SEO for that website. I wanted to know if does same domain name affects the SEO performance of the Website.

Hello Everyone, I wanted to know if a Domain like (xyza.com and xyzb.com) with the same name but with a different Url is there and if the majority of the traffic of going to the first domain(xyza.com). How should I do SEO for the second website? Thanks and Regards.