Only if you keep your current place, if you sell that, you'll pay standard rate. If you buy now and don't sell the current place, you'll pay the extra. If you sell the current one a bit later, I think up to a year, maybe 2, you'll get a refund.
Basic rule of thumb is, no matter how many property's you own, if at the end of the buying/selling, you have the same number of property's, you don't pay. If qty goes up, you do