I'd have a vet take a look at it.
I think fatty lipomas are relatively common in older cockers. My friend has a senior male cocker who was dumped in a shelter when his owner passed. He's somewhere around 16 now, and he has a soft ball size lump on his side.
I had a rescue cocker in, that had a huge lump on her neck. It was just a fatty lipoma. The vet tech told me it was weird - popped out like an egg when they made the incision.
With your dog having two pop out, I'd have a vet check her to be sure it's not something to be concerned about.
I had an older cocker who had one up around his arm pit. We didn't worry about it right away, as he was older. It started getting bigger and affected the swing of his leg when he was walking. At that point, we opted to have it removed before he got any older. It was just a fatty lipoma.