Run to the end, then merge is the sensible way but people just can’t manage it and it all gets stressy so I don’t try it on generally. On the road I use where it tends to happen, I’ve only just joined so I’d feel a right git pulling out.
Frankly, I’m generally pleased when somebody “blocks” the empty lane – esp when the consequence is that both lanes fill up behind them (I mean, that’s what we all want, right ? 😉 ). Also, the cross people in flash cars then just add to the fun for me.
On roads where it happens routinely they should put up signs telling people to do so, like those in the pic above (use both lanes and merge at the end ONLY).
Tossers trying to get ahead at others’ expense do, of course, exist but they’re more obvious when shoving in late at an exit or undertaking a queue and then shoving out.