MY 7 week old golden retriever was darker sploaches of skin on her tummy... is this normal?

I noticed that no one answered your question and I didn't want to think you were being ignored. Sometimes questions slip through the cracks here.

Yes, it is totally normal for our pets to have different skin pigmentations on different areas of their body. Nothing to worry yourself over. Hope you have a lot of fun with your new baby! :)

P.S. It is always wise to have a vet check your dog over and make sure everything is okay, shots/deworming have been done and to give the doc an overall baseline on your pets health for future issues.