If the accident is not your fault, you should not have to pay the deductible. The 'at fault' driver's insurance is responsible for paying for all the damages to your car. Even though you and the 'at fault' driver have the same insurance, it often helps to view the situation as if you and the other driver actually have different insurance companies.
Perhaps you are talking to 'your' insurance adjuster instead of the other driver's insurance adjuster when being advised of this deductible issue. If you ask your adjuster to make the repairs, then the repairs are covered under your collision coverage, and you do pay a deductible. (The ridiculous part of this is that, typically, your insurer would then turn to the other insurer to get full reimbursement - and usually get reimbursement for your deductible.)
To avoid this issue, however, you should just make sure you are talking to the insurance adjuster who is handling the 'liability' claim for the 'at fault' driver. That adjuster should make arrangements for the repairs without you having to pay a deductible.
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