The current version of the Ideas & Feedback Portal doesn't restrict the number of votes a user can place. We considered that feature, but decided to release version 1 as early as possible, which meant deferring some features. You can currently change your vote on an item, in case you change your mind about something after you've voted.
We'll soon be making an instance of the Ideas & Feedback Portal public, so we can gather feedback for TeamPulse. When we do, I encourage you to place that idea in there and vote it up.
the Telerik team