For someone accustomed to watching the SE, which has only one saber ignition, it would certainly seem like a glitch.

Whether they did it on purpose, or if it actually is a mistake, is impossible to say for sure. But every mix ever made of the original version of the film has the double ignition, so there's no way I'd ever try to remove it.

Actually, the funny part of it is that by removing the double ignition, the SE introduces a far worse glitch into the scene, which is that the subsequent sound effects become out of synch to the picture. They now happen too early, by the same amount of time that the removed first ignition sound would have been. Consequently you can hear the sound of Luke cutting himself free from the ice before he is actually seen to do so, as well as deactivating his saber while it is still obviously lit onscreen.

That's just plain sloppy work, and this mistake has been there since 1997. Yet another example of why redoing something that is already complete can be a very slippery slope—you forget why you did things a certain way the first time, and in trying to correct perceived imperfections, greater errors may easily be introduced that were never present previously.