I have two PCs that have the same applications installed, but the version of some of the applications is different between the two PCs. So, I need to identify an application whose version is different between the two PCs by comparing the version of each of the applications in one PC with the version of a corresponding application in the other PC.
I would like to know the usage of article for the bold word "an application". In the example, the number of applications whose version is different between the two PCs is undefined yet (i.e., may be only one or may be more than one) because the identification is not started yet. In such a case, do native speakers use a singular form or a plural form?