Folks, we've really ought to acknowledge that there's a usage of 'phase' in the electrical industry that just doesn't appear in most dictionaries. We use 'phase' to refer to a combination of two ungrounded conductors in a multi-phase generation and distribution system. Some people may use it in other ways (hot to neutral?) but I think almost all of us will agree that we use it in this way, and that such use is intelligible to other electricians and engineers.
No matter how hard you try, this is not equatable to mathematical definitions of phase (e.g. angular quantity). And no matter how hard you try, there's no way you are going to get electricians or even engineers to stop using this electrical meaning of 'phase'. (Hopefully we can discourage people from calling one wire a phase, as some do, and encourage them to call it a leg. But that's another question.)
So as for rattus' question, my answer is no.
'In phase' means synchronized. We don't use the preposition 'in' to mean something else.
'Of the same phase' can refer to a mathematical phase or an electrical phase. One can create about as many electrical waveforms as one pleases from a single electrical phase (two conductors). Those waveforms may or may not be of the same mathematical phase, but they can be considered all 'of the same' electrical phase that powers them. So you'd better just say which you're referring to -mathematical or electrical phase - if you're not sure how your interlocutor is going to interpret it. Especially if you're making a technically important distinction ... which, thankfully, you probably won't be making much in real life. :roll: