particles - 「が」 meaning “or”

I found this sentence in a game manual:

16回に１度、グリーンがブルーのかわりに出現。

Unfortunately I don’t understand why there is 「が」 used between the two color names. The sentence clearly means that this red candy appears every 16th time instead of a green or a blue one. Because of that I’d expect 「か」 instead.

My guess would be that this is just a typo and there should really be 「か」. It wouldn’t be the first typo in this book. However I don’t feel proficient enough to be sure.

Is the 「が」 a mistake, where 「か」 should have been used, or does it really mean or (or something else) here?

Update:

I added the description of the two candies references in the red one’s description. Now it should be clear, that these two (blue and green) types of candy do not appear every 16th time, but on a different occasion.

［ブルー］バブルんが一定回数アワをはくと出現する。
［グリーン］バブルんが一定回数のアワを割ると出現する。

The blue candy appears when player shoots a certain amount of bubbles. The green one appears when player pops a certain amount of bubbles.

Because of that I’d expect that the red candy would appear when either a blue or a green candy should appear for the 16th time.

Answer

guys! I am a Japanese living in Tokyo.

I totally agree with the idea that this is a typo. But it might be fair to say that the proofreader of this manual overlooked. It is quite confusing because the existent sentence literally makes sense.

16回に１度、グリーンがブルーのかわりに出現。

= Once every 16 times, a green one will appear in replace of a blue one.

But this description doesn't refer to a red one, which is strange. Maybe the correct one is like this (The hypothesis of Glutexo is completely right I think.)

16回に１度、グリーンかブルーのかわりに出現。

= Once every 16 times, (a red one) will appear in replace of blue or green one.

This completely makes sense when it comes with an image of a red candy ball. The proofreader made mistake not because he looked over a typo but he didn't understand the system of the game. And things like this frequently happen due to a feature of Japnese grammar, which we can omit the subject word. (ex. there was not a word of "red one", right?)

BTW, I found an interest on this game itself, what is the name of the game? And who published? I am a candy lover writing a blog Japanese Candy SAMURAI. And I would like to know about this game of candy!