A method for identifying a nucleotide in a primed template nucleic acid, including the steps of (a) providing a vessel having a primed template nucleic acid, polymerase and a nucleotide cognate of a first base type; (b) examining the vessel for a stabilized ternary complex including the polymerase and the nucleotide cognate of the first base type bound at a base position of the primed template nucleic acid; (c) delivering a nucleotide cognate of a second base type to the vessel, whereby the vessel retains the primed template nucleic acid and the polymerase from step (b); (d) examining the vessel for a stabilized ternary complex including the polymerase and the nucleotide cognate of the second base type bound at the base position of the primed template nucleic acid; and (e) identifying the type of nucleotide at the base position of the primed template nucleic acid.