If I go to the bathroom before I take a shower and immediately go in the shower [it is right next to the toilet], and after the shower i go to he bathroom again, what happens to the first asher yatzar?
Although the opinion of many poskim is that one shoud recite asher yatzar twice in succession for using the bathroom twice, this only applies when there is a hesech hadaas in between the two uses of the bathroom. If one uses the bathroom twice without leaving the room, this would not be considered a hesech hadaas, and one would only recite the blessing once.
Sources: Many poskim maintain that two uses of the bathroom obligate two recitations of asher yatzar. See Shulchan Aruch, Orach Chaim 7:2; Rema; Taz; Eliyah Rabbah; among others. However, Kol Gadol (89) and Eliyah Rabbah (7:2) write that if one does not leave the bathroom in between, this would not be considered a hesech hadaas, and one would make only one blessing even according to this opinion. This would probably apply even if one takes a shower in between. It should be noted that other opinions maintain that one should never recite the blessing twice in succession, even when there is a hesech hadaas in between uses of the bathroom. This is the opinion of Bach (7), Olas Tamid, Shelah, as cited in Eliyah Rabbah.