If there is a common mechanism for triggering dual boot, they would know about it and try it out too. So, not unless you use a unique, inconspicuous mechanism.
For example, I believe Truecrypt has a dual container system with two passwords in addition to their regular encrypted containers. You enter one password to get to the "fake" container and another password to get to the "hidden" container. Plausible deniability exists where it is impossible to prove whether you are providing the hidden password and whether there is a second hidden container.
Could a similar system be employed for a mobile device? The core OS components could be shared by both containers and it's clear that you could potentially have a second hidden profile, but it's not possible to prove that it exists.
Of course just the presence of countermeasures on your devices would raise suspicion.
If you're at the point where this seems like a good idea, you're better off not bringing data over the border.