I have a radio tuner on my cd player, and I try to tune into one station (college stations) from home, but it isn’t the same station as I get in my car. I’ve also tried tuning it in my car, hoping it was just my position, but again, it is different stations. Is it becuase of the fact my car can recieve the signal better, while my portable radio isn’t capable of it? Is it also the fact that these college stations are relatively weak, and the stations I hear on my portable is just different stations that happen to be recieved at that frequency?
Without a bit more information, I can’t be absolutely sure, but it sounds as though you are catching some of the low-end public access channels. A lot of high schools (and some colleges) have stations that are licensed to broadcast using hundreds of watts (instead of thousands of kilowatts) of power. This allows the FCC to license many more of them near each other because they have a hard time interfering with each other. I would think that if your car was just outside your window, the car and in-house radios should get the same stations, but that if you tune in from the car just a mile or two away from home, you could be getting a completely different station.
Do you have a digital display or a dial to indicate frequency?
Radio stations are required to announce their call letters and frequencies from time to time - are you sure both stations are on the same frequency? If so, they are most probably of the low-wattage variety.
Anybody want to guess how a tuner selects which signal to output when there are >1 on the same frequency and modualtion technique?
I’ve got a EE degree. I don’t need to guess. 
If they are using amplitude modulation (AM) then the receiver does a band pass filter around the desired frequency and demodulates whatever it finds in that frequency range. Speaking english (rather than electrical geek) what this means is that all signals in that frequency range are added together and make a composite signal, or in other words the two stations will add together and you’ll hear both. It’s kind of the nature of the beast with AM. There’s no easy way to discriminate between the two signals.
If they are using frequency modulation (FM) then the radio signal varies back and forth a bit in frequency to encode the signal. To decode this signal, the receiver has to lock onto the signal and track the way the frequency shifts. The receiver will lock onto whatever signal is stronger, and will completely ignore the weaker signal. If the signals are relatively close in strength then the receiver may get confused, and will track one or the other alternately, depending on which one is the strongest at the time. You will hear both stations but they will each be choppy, as the receiver is alternating back and forth between them and not just adding them together like it would with an AM signal.