When a draft is deployed, the changes in the draft are applied to what is currently deployed to the Environment. This means that your draft will usually remain valid even if another developer has made a deployment to the environment between you creating your draft and deploying it. As long as the changes in the first draft don't conflict with the second (for example the first draft removes an item which needs to be updated by the second draft,) the second deployment will succeed and apply the changes you had in your draft. This is similar to how patches can be applied to a code base. Multiple patches can be applied as long as they do not conflict with each other.