I would classify Cleopatra as not a box office bomb, but more of a film that allowed "cost to make it" be so high, it was impossible for the studio to make a profit from just its initial theatrical run. Spending 44M back in the early 60s to make film is like spending over 400M today to make a...
I don't know what you mean by technically different, but did you read RAH's first post in this thread which is his review of this disc in comparison to the UK release?