Thanks for the issue and PR, I'll likely merge this but don't have the time to see it through today. It would be a semver major change, and I want to do a few maintenance things for the same release that might be a day or two of work. Once I finish dogfooding the coming new graphql-react in some large codebases and publish it I'll have a chance to catch up on things like this PR.

In the meantime, as discussed in #251, multiple installations of apollo-upload-client can be avoided by ensuring only one version is specified in the project lockfile. Deduping dependencies in a lockfile is something everyone should always do anyway, or you will end up with massively bloated node_modules and bundles. I always delete my lockfile and regenerate it from scratch when updating dependencies to avoid bloat, although as you mentioned in the issue there are other ways to do more targeted updates with deduping.

Thanks for your work, this change has been published in v15 🚀