Coupled parametric oscillators have been recently employed as simulators of artificial Ising lattices, with the potential to efficiently solve important minimization problems. Here, we report on a detailed study of two coupled degenerate parametric oscillators, exploring the entire phase diagram, in terms of pump power, phase and coupling strength, both analytically and experimentally in a radio-frequency (RF) experiment. In addition to a regime where the oscillators act as coupled spin-1/2 degrees of freedom, in the vicinity of the oscillation threshold there is a very wide range of parameters where the spin-1/2 description does not apply and the oscillators never reach steady state, but rather show persistent, full-scale, coherent beats, whose frequency reflects the coupling strength. Our study unveils the rich coherent dynamics of coupled parametric oscillators and is relevant to the topic of Floquet time-crystals in many-body systems.