In Guyana, there have been two plants related to iboga that has been identified according to
Iboga: The Visionary Root of African Shamanism. Sounded familiar so perhaps these are the plants you have heard of fractal?
tabernaemontana albiflora
tabernaemontana angulata
Whether or not these have been used in ayahuasca admixtures is new information to me but otherwise have always been told to keep SSRI type meds away from MAOI's. However, RIMA are relatively safe compounds. As though harmaline and ibogaine are structurally identical, the physical 'observed' anti-addictive properties will have been inversed in the NMDA channel by both chemicals. As though ibogaine itself binds to all receptor sites, it would definitely not be wise to mix the two to flood the body, metabolism will increase heart rate, blood pressure rise, and so forth..
Never had a personal relationship with iboga but otherwise would be interesting to hear some more about the mixture of ayahuasca and ibogaine. The amounts of ibogaine in these two plants are minute compared to what is found in tabernanthe iboga so if it they are used in a ceremony I would imagine that a very small amounts would be used as well.
In the end we will conserve only what we love. We will love only what we understand. We will understand only what we are taught. ~Baba Dioum