As you know, Instagram features only comments and likes. You can not share another user's photo with a single key like Twitter or Facebook. Instead, there are so many people who take screenshots, crop other areas and share the same image ...

There is a solution to this situation. Now we can say that Instagram has the Repost feature. The app is available free of charge for both Android and iOS. Quite easily we can repost other users' shares.
There are three different applications to easily perform reposting. These are InstaRepost. With InstaRepost you can reshare your stream's posts. During sharing, you can also add the first user's username as a watermark. There is also a search feature that allows you to share the original state of the photo.

Android: https://play.google.com/store/apps/details?id=com.instarepost&hl=t is
iOS: https://itunes.apple.com/us/app/instarepost-repost-share-discover/id576764625?mt=8
The second application is Repost for Instagram. I think the application provides a better watermark and the sharing process is simpler.

Android: https://play.google.com/store/apps/details?id=com.redcactus.repost&hl=t is
iOS: https://itunes.apple.com/us/app/repost-for-instagram/id570315854?mt=8

With RepostWhiz application you can repost both photos and videos. RepostWhiz offers more features than other apps and has the ability to schedule extra repost and track other users. So if you love the interface, you will not need it even if you delete the Instagram from your phone.
Android: https://play.google.com/store/apps/details?id=com.repostwhiz&hl=t is
iOS: https://itunes.apple.com/us/app/repostwhiz/id765955840?mt=8