  We study cosmological models described by a single real scalar field. We work
within the first-order framework, and we show how the first-order equations
simplify the investigation, leading to a direct search of twinlike theories.
The procedure is used to introduce distinct models that support the same
first-order equations, with the very same energy densities and pressure in flat
spacetime. The presence of curvature forbids the construction of twinlike
models in the cosmological scenario here investigated.
