A method of identifying the base type at a position in a template nucleic acid, comprising steps of: (a) contacting a primed template nucleic acid with a polymerase and a first mixture of nucleotides under conditions for stabilizing a ternary complex at a nucleotide position in the template, wherein the first mixture comprises a nucleotide cognate of a first base type and a nucleotide cognate of a second base type, wherein said nucleotide cognates are attached to exogenous labels of the same chemical structure or to different exogenous labels that produce an overlapping signal such that the signals are ambiguous; (b) contacting the primed template nucleic acid with a polymerase and a second mixture of nucleotides under conditions for stabilizing a ternary complex at the nucleotide position in the template, wherein the second mixture comprises a nucleotide cognate of the first base type and a nucleotide cognate of a third base type, wherein said nucleotide cognates are attached to exogenous labels of the same chemical structure or to different exogenous labels that produce an overlapping signal such that the signals are ambiguous; (c) examining products of steps (a) and (b) for signals produced by a ternary complex that comprises the primed template nucleic acid, a polymerase and a next correct nucleotide, wherein signals acquired for the product of step (a) are ambiguous for the first and second base type, and wherein signals acquired for the product of step (b) are ambiguous for the first and third base type; (d) disambiguating signals acquired in step (c) to identify a base type that binds the next correct nucleotide. (a) contacting a primed template nucleic acid with a polymerase and a first mixture of nucleotides under conditions for stabilizing a ternary complex at a nucleotide position in the template, wherein the first mixture comprises a nucleotide cognate of a first base type and a nucleotide cognate of a second base type, wherein said nucleotide cognates are attached to exogenous labels of the same chemical structure or to different exogenous labels that produce an overlapping signal such that the signals are ambiguous; (b) contacting the primed template nucleic acid with a polymerase and a second mixture of nucleotides under conditions for stabilizing a ternary complex at the nucleotide position in the template, wherein the second mixture comprises a nucleotide cognate of the first base type and a nucleotide cognate of a third base type, wherein said nucleotide cognates are attached to exogenous labels of the same chemical structure or to different exogenous labels that produce an overlapping signal such that the signals are ambiguous; (c) examining products of steps (a) and (b) for signals produced by a ternary complex that comprises the primed template nucleic acid, a polymerase and a next correct nucleotide, wherein signals acquired for the product of step (a) are ambiguous for the first and second base type, and wherein signals acquired for the product of step (b) are ambiguous for the first and third base type; (d) disambiguating signals acquired in step (c) to identify a base type that binds the next correct nucleotide. <EOS>