This disclosure includes compositions for avoiding pipetting error when pipetting multiple different synthetic polynucleotides (e.g., quantitation controls) into a biological sample. A Conjoined synthetic standard may contain different numbers of copies of two different synthetic polynucleotides that are physically linked in a single polynucleotide sequence (e.g., using linkers). The physical linking can effectively fix the concentration ratio between the first synthetic polynucleotide and the second synthetic polynucleotide, e.g., when the conjoined standard is put into the sample comprising the target polynucleotide. This is in contrast to separately putting two different synthetic polynucleotides into a sample, which can be biased by pipetting errors.