Not sure what you mean in your post.
You can use the Companion Coupon from the AGR card on the rail fare portion of a sleeper trip. It won't get you a second room.
Here are the terms and conditions of the companion coupon from the AGR CC.
- Coupon valid for one (1) free companion rail fare with the purchase of one (1) regular (full) adult rail fare. Free companion and paying passenger must reserve at the same time and travel together at all times.
- Each coupon is valid for travel as one (1) one-way reservation.
- Travel blackouts apply: November 22-23, 2022; November 26-28, 2022; November 21-22, 2023; November 25-27, 2023.
- Valid for travel on all Amtrak service except train/Thruway series 7000-8999.
- Free companion offer is not combinable with any discount, coupon, or Amtrak Guest RewardsŪ redemption travel.
- The Coupon# is unique to your coupon and valid for one use only. Buying or selling this coupon is prohibited and will invalidate the coupon. Coupon may be transferred to a family member or friend.
- Offer valid for Coach class or Acela Business class. Upgrade to Business class or Acela First class is available upon full payment of applicable accommodation charges.
- Offer also valid for private rooms including Roomettes, Bedrooms, Bedroom Suites and Accessible Bedrooms; offer excludes Family Bedrooms.
- Other restrictions may apply.