This paper presents the measurements and analysis of linear plasma nonuniformities in the preliminary two target coupling experiment for the recombination pumping schemes performed on the LF12 laser facility. A pinhole transmission grating spectrograph (PTGS) was used to monitor the linear plasmas. Quite different nonuniformity features were observed between linear plasmas produced by one target and two target coupling. The effects of plasma nonuniformity on GL (product of gain and length) value are of great importance.