No, once a campaign is in an active state "Redeemable" option will be greyed out on step "Whom" when editing the campaign.
You can make edits to the chosen redeemable by clicking "Edit" under the greyed out "Redeemable" option (shown below in red) or from Settings > Redeemables, but will be unable to switch the redeemable out with a different redeemable.
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