I was working on a custom SharePoint master page, few days ago. After deploying the master page in Gallery, I set it for my site-collection. I had started facing a strange error i..e master tag is already defined. Initially I thought, that SharePoint existing pages, inherited from some other master page and I might override it, but it also didn't work.
After some time, I started looking my master page html, I had a commented master tag, which I believe should not be rendered by SharePoint, as commented. I removed the commented tag for testing purpose, and surprisingly things starts working. SharePoint engine actually render the commented tag as well.
I hope this post will help any newbie in SharePoint world..... Happy Coding.....:)
