When editing registration options for an event benefits will accumulate as opposed to being replaced on the benefits tab of the constituents event record.
We’re currently evaluating this issue for a fix in a future service pack.
Steps to Duplicate
1. Navigate to any event. 2. Add two different registration options, each must have a benefit associated. For ease of testing, make each benefit $0. 3. Register someone for the event, giving them the first registration option. 4. On the registration tab for that person, click to edit the registration option that you chose. 5. Change that registration to the second registration. 6. Navigate to the Benefits tab and see that the benefits did not replace with the newly associated benefit, but rather they accumulate from both registration options. 7. Edit the benefits, and edit the value then try to save.