Use a different value for the target attribute for each link if you want them to open in different tabs, the same value for the target attribute if you want them to replace the other ones.
the target = _blank is will open in new tab or windows based on browser setting.
To force a new window use javascript onclick all three parts are needed. url, a name, and window width and height size or it will just open in a new tab.
will open it in a new tab or window. As for which, it depends on the users settings.
<a href="http://www.starfall.com" target="_self">
is default. It makes the page open in the same tab (or iframe, if that's what you're dealing with).
The next two are only good if you're dealing with an iframe.
Since web is evolving quickly, some things changes with time. For security issues, you might want to use the rel="noopener" attribute in conjuncture with your target="_blank".
Like stated in Google Dev Documentation, the other page can access your window object with the window.opener property. Your external link should looks like this now: