If I wanted to work in Nigeria, I would send my application to both companies and then work for the one that hires me
If you get two firm offers, it will be much easier to compare them. If you get one offer, it's quite easy to chose. As they say: -It's easier to say no to something you've been offered, than yes to something you didn't get.
And if it turns out you picked the wrong company, the opposition will probably hire you after a year or two if you want to. (Just a guess, never been to Nigeria or know anything about CHC & OLOG)
Good luck!
/2beers