What's the purpose of using more than culture medium for bacterial isolation?
Why not use just one?
If this is not generally used in isolation of various types of bacteria, I'm concerned especially with Acinetobacter spp. isolation, which grow well on blood agar and MacConkey agar.
Examples of research which include the isolation of acinetobacter spp.:
In this study, 200 (9.5%) Gram-negative, non-fermentative strains were selected among 2108 Gram-negative isolates identified at mega laboratories over the Suez Canal and Nile Delta regions in Egypt (1044 urine culture, 108 pus, 537 sputum, 322 blood, 23 cerebrospinal fluid, and 74 wound) from August 2017 to October 2018. The 200 strains were preliminary inoculated on MacConkey agar, blood agar, Acinetobacter agar, and CHROM agar media. 
The samples were collected from patients of all age groups, both sexes, who were critically ill and suspected for pneumonia, urinary tract infection, septicaemia, skin and soft tissue infection and meningitis. The samples were inoculated on Blood Agar and MacConkey Agar plates under strict aseptic conditions. 
All the samples including bland pus, respiratory tract samples, fluids, swabs and urine samples were surface streaked onto BA [Blood agar] and MacConkey agar plates. 
- Oberoi, A., Aggarwal, A., & Lal, M. (2009). A decade of an underestimated nosocomial pathogen - Acinetobacter in a tertiary care hospital in Punjab.
Edit: There is one species in the genus Acinetobacter, Acinetobacter haemolyticus, which causes beta hemolysis on blood agar, however, not a single research that mentions using both MacConkey and blood agar, mentions this as the reason for using blood agar.