Open multiple tabs in Chrome via bookmarklet
They both open at the same(or close to) time with that code, change the delay or embed one in the other.
setTimeout( function(){ window.open(url1) }, 10); setTimeout( function(){ window.open(url2) }, 20); setTimeout( function(){ /* any other code with window.open() */ }, 30);
Chrome runs each tab as a separate sandboxed process - when you click a bookmark, it can only take action within that tab.
That leaves you with the option of opening the second tab from the html/js of the first, but this will be blocked by the popup blocker unless it is prompted by a user action.