Coherent photoproduction of two neutral pions on the deuteron and ^3He is calculated. The isoscalar and isovector parts of the elementary photoproduction amplitude was determined by fitting the measured total cross section on protons and neutrons. Th
e dependence of the cross section on the isospin of the target nucleus is discussed.
Angular distributions in the final state of pi0-eta photoproduction on nucleons are considered. As a formal base the familiar isobar model is used in which the (pi0 eta N) state is a product of the resonance decay into eta-Delta(1232) and pi-S_{11}(1
535) channels. One of the principal assumptions used is that in the actual energy region the reaction is dominated by a single resonance state. The developed formalism can serve as a tool for testing spin and parity of that resonance.
