RSRP-468993: Encapsulate Field: New property is not created when property which encapsulated field already exists.

JetBrains ReSharper Ultimate 2018.1 EAP 6 D Build 12.0.20180330.53424-eap06d

        private string myString;

        protected string MyString
        {
            get { return myString; }
            set { myString = value; }
        }

        public void DoSomething(string input)
        {
            myString = input;
            var test = myString;
        }

1. Invoke Encapsulate Field on myString field.
2. In "Encapsulate Field" dialog set "Create new property" as "Choose property:"; "My" as "Property name:"; uncheck "To auto-property".
3. Click Next

Actual result:
New property is not created.

Expected result:
New property is created.