Can someone who gets the honor of taking out the Sefer Torah also get an Aliyah? I ask because perhaps there is an idea that someone should only get one Kavod by Sefer Torah.
It's possible to run into a situation in which you have no choice but to double up. For an extreme example, suppose you have a minyan of exactly ten men, and it's a Shabbat on which you take out three Torah scrolls. Then, your Torah service honors include seven regular aliyot, maftir, opening the ark, two Torah-carriers, three hagbahas, and three gelilas, for a total of seventeen honors to distribute, meaning that seven of the men will need to get two honors.
(I don't know if I've ever run into a situation this extreme, but I've definitely experienced having to double-up while serving as gabbai at my college minyan.)
I don't have a source to prove that aliya and opening the ark, in particular, can both go to the same person, but it seems, intuitively, that if something has to get doubled-up, opening the ark, which is the honor least coincident with the rest of the Torah service, would be a reasonable choice.
Yes. I've been in a good number of orthodox synagogues in which the same person took out the Torah scroll and received an aliya. These include Young Israel of St. Louis (Mo.), Agudas Israel of St. Louis (Mo.), Agudath Israel of Madison (Brooklyn, N.Y.), and Beth Avraham Yoseph of Toronto (Ont.).