Multiple/repeated builds per git push

I have just started using automated build connecting to Bitbucket. My project contains multiple directories with a single Dockerfile each. After configuring Build Settings (including adding repository links to base images), automated builds for all Dockerfiles are triggered upon git push.

The only problem I am having is that multiple and seemingly identical build requests are queued upon a single git push. The Build Details page shows 3 builds are queued per Dockerfile. Is this an expected behavior? If not, how can I fix this? One of the images takes about 30 minutes to build, so having 3 of them is inconvenient.