A Missing Textual Variant from Mark 6:7-8

Checking the photographs from Sinaiticus about Mark 6:11 (about which, see this post) I noticed a textual variant in Mark 6:7-8 that does not appear in any of the editions. Instead of

καὶ προσκαλεῖται τοὺς δώδεκα, καὶ ἤρξατο αὐτοὺς ἀποστέλλ ειν δύο δύο, καὶ ἐδίδου αὐτοῖς ἐξουσίαν τῶν πνευμάτων τῶν ἀκαθάρτων, καὶ παρήγγειλεν αὐτοῖς ἵνα μηδὲν αἴρωσιν εἰς ὁδὸν εἰ μὴ ῥάβδον μόνον, μὴ ἄρτον, μὴ πήραν, μὴ εἰς τὴν ζώνην χαλκόν,

 Sinaiticus has

καὶ προσκαλεῖται τοὺς ιβ, καὶ ἤρξατο αὐτοὺς ἀποστέλλιν δύο δύο, καὶ ἐδίδου αὐτοῖς ἵνα μηδὲν αρωσιν εἰς ὁδὸν εἰ μὴ ῥάβδον μόνον, μὴ ἄρτον, μὴ πήραν, μὴ εἰς τὴν ζώνην
χαλκόν,

 The phrase ἐξουσίαν τῶν πνευμάτων τῶν ἀκαθάρτων, καὶ παρήγγειλεν αὐτοῖς is actually missing from Sinaiticus and inserted in another hand at the top of the page. This is a clear case of haplography (the accidental omission of material) due to homoteleuton (same ending of a string of characters). The scribe's eye has slipped from one occurrence of αὐτοῖς to another causing the intervening material to disappear from the text. Sinaiticus is a beautifully written manuscript, but the scribe who wrote it was very careless and prone to omit material. When one sees that Sinaiticus is missing material one's first inclination should be to blame the omission on scribal error, such as in this case.

If the King James Version had followed Sinaiticus in this passage it would read:

And he called unto him the 12, and began to send them forth by two and two; and gave them power that they should take nothing for their journey, save a staff only; no scrip, no bread, no money in their purse:

Nestle-Aland and UBS usually note what is in the original hand of Sinaiticus and what was added by which corrector, but nothing of the sort appears here.  This is also an example where a textual variant potentially makes a difference.