Same house on rightmove twice

This can happen because it’s on with different agents. Sometimes they’ll have different prices and this might be because land is being separated off from one of them. It’s always worth reading both sets of details and working out what the differences are.
The more agents a property is on with though, the more desperate they are to sell in my opinion. It might be they don’t want to lower the price to get viewings and so believe another agent will get them a sale without them dropping their price.