Hi and welcome.
Your hamsters, if they came from Pets@Home will be hybrids somewhere along the line as the hamster mill they come from does not have pure lines. Some of the health issues such as diabetes can be attributed to this hybrid breeding. Hybrids come in a mish mash of colours and patterns so that will be why they do not look alike. They cannot guarantee these were litter mates as they will all have come in a big batch from the supplier.
They still make lovely pets though.
Now down to your problem. No it is not normal for them to smell badly like that or have soft poo. They sound like one at least has a bowel infection and I think you need to take them both to a vet to have them checked out and they will likely prescribe Baytril. I also think you need to have them tested for diabetes as the amount of urine you describe is not normal.
You could try going to P@H and buying some ProC powder which is a probiotic and this may help to improve the good gut bacteria in the bowel. You need to change the water every day with this. I would take them off the P@H food as it contains too much added sugar for dwarf hamsters. Try Harry Hamster (from Wilkos) and add supplements such as linseed, lentils, bulgar wheat, flaked soya, millet spray, budgie seed.
If the vet does give meds then make sure you give by syringe into the mouth not in the water as they dont get enough done that way.
Dwarfs do have a terrible habit of peeing in their wheel then running in a piddle shower so this may be contributing to the smell. Wash the wheels (you should have two for a pair) daily. Give a sand bath with charlie chinchilla sand in it to help keep them fresh too.
There is an article 'is my dwarf diabetic?' on the WIKI so check that out.
Hope that helps
