Instagram currently doest have any feature for switching among multiple accounts.
But it seems it is under way, as some of the iOS users are able to use this feature. According to Latergramme ,If you have access to more than one Instagram account, you can add each one in the app’s settings and switch among them as you see fit.
There were some screenshots some users posted to Latergramme’s Facebook group giving the glimpse of the new feature that maybe can be live soon for everybody.
This feature will totally separate everything which include stuff like photos, comments and messages etc. Even notification for like or comment will will indicate which account they are coming from.
A beta version of the feature appeared on Android devices in November, Engadget notes, but that required downloading and manually installing an APK package.
Allowing multiple users can increase the number of spamming and fake accounts on instagram but this can turn out to be a good feature for people who have separate account for the business use and personal use.
This features is currently for some very few amount of people using iOS which means that this is either a beta test or a gradual rollout.