Hi, as long as your previous petition was approved another petition can be filed for you and your previous priority date can be applied to your new petition. Make sure you give a copy of your previous approval notice to your new sponsor as it is much easier to get the old date applied at the time of filing your new petition. If you have to go back to the NVC afterward to get it changed it could take months. As long as you only continue with one petition it will not affect your fiancé filing a petition for you too. You can see which one is approved the quickest and at the time you are requested to pay the visa fee choose which one you want to go with.