Answer: It sounds like winter damage. If only the leaves, but not the branches are involved, you can simply allow the plants to recover on their own. They will sprout new leaves along the branches as long as the branches were not killed, as well. It's always a good idea to wait before pruning - sometimes latent buds will generate new leaves along bare branches. Once you're sure the branches are dead - you can prune them off. Your hollies are planted very close. If you have room to move one of them, I'd recommend doing so. If space is at a premium in your garden you can leave them where they are. They will simply grow into one another and look like a single shrub with two trunks. Hollies are very adaptable in that manner.
Best wishes with your landscape!
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