Culture-based Salmonella isolation consists of nonselective pre-enrichment, followed by selective enrichment in Rappaport–Vassiliadis (RV) or tetrathionate (TT) broths, and subsequent plating on selective indicator agar. This study aimed to assess the recovery of two strains belonging to serovars Montevideo (strain ATCC-8387) and Typhimurium (strain ATCC-14028) when grown together in different media. The two strains were co-inoculated 1:1, 10:1, 100:1, and the reciprocal, and CRISPR-SeroSeq was used to assess the relative frequency of both strains after each culture step. Individually, there was no growth difference between both strains in universal pre-enrichment (UP) or RV broths, though both strains had a higher growth in the former. In TT, both strains had reduced growth, especially ser. Montevideo-8387. When the strains were combined, the growth of ser. Typhimurium-14028 strain was higher in UP and TT broths, while the ser. Montevideo strain was higher in RV broth. The ser. Typhimurium strain also grew better on xylose lysine tergitol-4 (XLT-4) agar. Using media that are commonly used for Salmonella isolation, this work reveals strain-to-strain differences in growth and that in three conditions (UP, RV, XLT-4), these differences were only manifested when the strains were in competition with each other. These findings illustrate the importance of dual selective enrichments to be able to capture all Salmonella present in a sample.