  There is a degeneracy in the radial velocity exoplanet signal between a
single planet on an eccentric orbit and a two-planet system with a period ratio
of 2:1. This degeneracy could lead to misunderstandings of the dynamical
histories of planetary systems as well as measurements of planetary abundances
if the correct architecture is not established. We constrain the rate of
mischaracterization by analyzing a sample of 60 non-transiting, radial velocity
systems orbiting main sequence stars from the NASA Exoplanet Archive (NASA
Archive) using a new Bayesian model comparison pipeline. We find that 15
systems (25% of our sample) show compelling evidence for the two-planet case
with a confidence level of 95%.
