In English, I can say:
I would like to have a house in France, and one in California.
the one is referring back to the original house, before the and splits the sentence.
Can I do the same thing in French? It always works on online translators, but they may be directly translating it. If it is valid, should it be un or une?
Je voudrais avoir aussi une gîte en France et un à la plage en Californie.
You can do the same in French. The gender must be kept unchanged.
Your first sentence might be translated as:
J'aimerais avoir une maison en France et une (autre) en Californie.
I would rewrite your second sentence like this:
J'aimerais aussi avoir une maison en France et une autre sur la plage, en Californie.
Note that it is un gîte, not une unless you are talking about a boat heeling which is obviously not the case here.
