A search was performed for the associated production of two different Higgs bosons via a virtual Z0 in e+e− annihilation (e+e− → h10h20) using the JADE detector at PETRA. This was motivated by the interpretation of the monojet events observed at the CERN p collider as anomalous Z0 decays into two neutral Higgs bosons (h10 and h20), where h10 is stable and escapes detection while h20 decays into hadrons. Single- or di-jet events with large momentum imbalance are then expected at PETRA energies. No evidence for such events was found in our data; this excludes h20 masses in the range of 1 to 21 GeV with 95% CL, if the branching fraction for Z0 → h10h20 is a larger than one half that for . The possibility that the monojets could originate from supersymmetric higgsino production from Z0 decay is also examined.