Knowing whether a mojave is a harlequin or not is about as possible as telling whether a tomato is red or scarlet. I'm not sure if it's even possible to tell the difference between a harlequin mojave and a typical mojave, since harlequins themselves are like normals with a mojave-like pattern. On top of that, harlequins still have no defined form of inheritance. WOB labels them as a Dominant mutation but I hear other people saying it isn't as predictable as that, with theories such as it being polygenic, not to mention it isn't compatible with some morphs. In my opinion, harlequins are more like a 'phase' as opposed to a single gene morph.
I will tell you one thing, harlequins are most notable for a reduced pattern and a decent ventral stripe, comparable to Borneo STP's that are bred for their stripes. That being said, my beautiful normal harlequin girl has a much longer, unbroken stripe and hell of a lot less alien heads than the girl you posted. I'd honestly say you should treat her and pay for her only as if she were a mojave and not jump on the conclusion she is a harlequin.