They're not free to move yet so they're still Accrington players at the moment. Signing pre-contracts with Rangers doesn't negate their existing contracts in any way. In pretty much any other line of work you're free to speak to potential employers without seeking permission from your current one at any time in your contract regardless of when any existing contract is due to expire. Clubs preventing players from speaking to other clubs until their contract has expired would put them at a huge disadvantage in the market compared with those who were allowed to do so.