A method of decoding solid supports, comprising: detecting a first encoding signal and a second encoding signal for respective solid supports in a plurality of solid supports, wherein the plurality of solid supports includes two or more different populations of solid supports, wherein the first encoding signal is detected at a first time point and a second encoding signal is detected at a second time point, and wherein detecting the first encoding signal at the first time point and the second encoding signal at the second time point for respective solid supports in the plurality of solid supports provides a number of encoding states for the plurality of solid supports that is greater than the number of encoding levels at a single time point measurement, and the number of encoding states is greater than the number of encoding levels at a single time point measurement; generating at least one chemical and/or physical change associated with the solid supports in the plurality of solid supports that is activated by a light source and/or a thermal source, wherein the first time point is prior to generating the at least one chemical and/or physical change associated with the solid supports and the second time point is during or after generating the at least one chemical and/or physical change associated with the solid supports; comparing the first encoding signal for an individual solid support in the plurality of solid supports and the second encoding signal for the individual solid support in the plurality of solid supports, wherein the first and second encoding signals for the individual solid support are different; and decoding the plurality of solid supports based on the comparison of the first and second encoding signals for respective solid supports in the plurality of solid supports to identify solid supports corresponding to each of the two or more different populations of solid supports, wherein decoding the plurality of solid supports includes comparing the first and second encoding signals for the individual solid support to determine the identity of the individual solid support. detecting a first encoding signal and a second encoding signal for respective solid supports in a plurality of solid supports, wherein the plurality of solid supports includes two or more different populations of solid supports, wherein the first encoding signal is detected at a first time point and a second encoding signal is detected at a second time point, and wherein detecting the first encoding signal at the first time point and the second encoding signal at the second time point for respective solid supports in the plurality of solid supports provides a number of encoding states for the plurality of solid supports that is greater than the number of encoding levels at a single time point measurement, and the number of encoding states is greater than the number of encoding levels at a single time point measurement; generating at least one chemical and/or physical change associated with the solid supports in the plurality of solid supports that is activated by a light source and/or a thermal source, wherein the first time point is prior to generating the at least one chemical and/or physical change associated with the solid supports and the second time point is during or after generating the at least one chemical and/or physical change associated with the solid supports; comparing the first encoding signal for an individual solid support in the plurality of solid supports and the second encoding signal for the individual solid support in the plurality of solid supports, wherein the first and second encoding signals for the individual solid support are different; and decoding the plurality of solid supports based on the comparison of the first and second encoding signals for respective solid supports in the plurality of solid supports to identify solid supports corresponding to each of the two or more different populations of solid supports, wherein decoding the plurality of solid supports includes comparing the first and second encoding signals for the individual solid support to determine the identity of the individual solid support.