Yes. With Switch Mode, you can change between One-Way Mode and Hedge Mode without closing open positions. Open positions will carry into the new mode with entry price, PnL, and margin intact. Active orders must be cancelled before the switch.
If you are switching from Hedge Mode to One-Way Mode, your long and short legs will be netted. For example, a 5 BTC long and a 2 BTC short will carry over as a 3 BTC net long in One-Way Mode.
A 5 BTC long in One-Way Mode appears as a 5 BTC long leg in Hedge Mode, ready to accept an independent short entry on the same contract.