Would having two words in my surname in my passport be a problem for US colleges/GRE/TOEFL?
I am Latino, and as a result have an even worse version of this issue. My full name is of the form
A B C D E, with A and B being given names, and C D  and E being surnames. An extra complication is that D is not a name by itself, it's just a preposition.
I have given the TOEFL and GRE tests before and that has not been an issue. Minor errors may occur depending on who handles the documentation, but they have never been an actual issue. For example, my names have been agglutinated as CDE, AB (surname, first name). In a visa, I had it once written as B C D E, A. In academic papers, it has been cited as E, A B C D; D E, A B C; C D E, AB; B C D E, A. The preposition itself sometimes vanishes leading to C E, A B.
No clerk has ever questioned my authorship, or my documentation in my travels.