You can clone a tab with right click on a tab and then clone a tab.

sidney, yes I know that and I'm sure OP knows that too. Did you read my previous post?

Option to clone the tab is already there on the tabbar, but clicking with MMB on refresh is much faster and more
comfortable.

And did you read request carefully?

Please add option to Clone a tab by clicking MMB on Refresh Toolbar button.

And i've never been able to understand the idea behind cloning a tab.

I will give you one example, when you are browsing a webpage which opens images in the same window via java script, middle click doesn't work and when you press back you are redirected to something unrelated or for example position on a webpage you were on is reset.
So if you know a page you are browsing works this way, you can just clone that tab ahead and open link/image without worrying much, after you close current tab you go to the cloned one and taaadaaa you were where you left before.
This happens on a poorly made websites with no way to close image, for example it should open in a popup, but instead opens in the same window.

Option to clone the tab is already there on the tabbar, but clicking with MMB on refresh is much faster and more comfortable. Chrome, Chromium (on Linux), SWIron, Superbird, Slimjet all have it. Mozilla and all Chromium browsers have it, so now question is; was it removed in Opera from chromium's source code or did others add that feature to their forks?