Shahrukh Khan hasn't resorted to stealing guitars for sure. The actor who was shooting for Mudassar Aziz's Dulha Mil Gaya shot with a red guitar that was taken from Salman Khan's set without his permission. The incident happened when Aziz and choreographer Ahmed Khan didn't fancy the red guitar supplied by the props supplier and asked for a replacement.
The only replacement available was with Salman Khan who was shooting for Wanted Dead And Alive. Since Salman was shooting on that day there was no way on earth that he would part with his guitar for a Shahrukh's movie. Then the prop supplier sneaked into Salman's set and replaced the guitar they had brought without anybody's permission.
Mudassar Aziz was relieved at the end of the shoot as after a long time he had Shahrukh's dates and did not want to mess up a shoot for a guitar. It is not known whether Salman Khan shot for Wanted with the other guitar. Well Salman has been trying to patch up with Shahrukh off late but this incident might not help thing towards their reunion.