In my current company we're using Scrum with 2 week iterations and a regular planning session. How planning normally works in our company is that we take a predefined , prioritized (by PO before the planning) product backlog of user stories / PBIs, take PBIs from the top one by one and break it down to tasks to then estimate them in hours (using poker planning and fibonacci) until we reach a given team's capacity.
While this works for most of the teams, there is one 2-person team where I'm a SM, that tends to systematicaly overestimate the tasks by far (as those developers are being paid by an hour in this project, and from the record of working with them in another project I know for a fact they have a far better velocity). Not being a part of this team as a developer, trying to adhere to Scrum I'm refraining from influencing those estimates by any means, however as we approach the deadlines in the project this situation is becoming more and more troublesome.
My question is - is there a way / good practice in such situations, to keep the team on the edge of their velocity and not influence their estimations, or maybe we're doing sth wrong in the process ?