"No puedes mantener las dos."
Translation:You cannot keep the two.
Spanish speakers frequently reference 'los dos' or 'las dos' in cases where English speakers would use the word 'both'. Additionally, I often hear my wife say things like "Espérate, los dos," which is basically her saying "Wait, both of you" or "Both of you wait." In this case, and partially because of my experience with those type of situations, I immediately understood the sentence to be referencing two of something, but translated like English speakers would say 'both'. There are probably many correct variations DL has added at this point, but in my opinion the most common and non-formal way to translate this sentence would likely be "You cannot keep/maintain both."
I understand the literal translation is what's given above, but it is rarely said that way in English. I entered: "you cannot keep both of them" and was buzzed for it. While, again, I recognize it is not the literal translation, it is how this phrase would most often be said by natives.
"In Spanish there is no difference, between ambas and las dos, " Edit. I've been corrected by my Spanish language learning partner. "Las dos" means "Both of them", not just both. There is a slight difference apparently. It makes sense, because "You can not keep the two" is archaic English for "You can not keep both of them"