Javascript - Date Auto-Population Help

A form that was previously working perfectly now seems to be giving me some grief with the New Year having come upon us. This form is set to start at the current month and go back one month concurrently as below:

1/2019   12/2018  11/2018  10/2018  9/2018

It was doing this until the new year of 2019 came up and now it's duplicating some dates and looks like..

1/2019  12/2018  12/2018  10/2018  10/2018

I'm looking for some help to fix this issue and get it back to the way it is meant to be updating.

Document level Javascripts are:

To get first field:

this.getField("Today").value = util.printd("mm/yyyy", new Date());   

To get other fields:

function getPastDate(Today, months){

    var v = this.getField(Today).valueAsString

    if (v=="") return "";

    var cDate = util.scand("dd/mm/yyyy",new Date("01/"+v));

    if (cDate== null){

        app.alert("Please enter a valid date of the form \"mm/yyyy\".")

        return "";

    } else {

        cDate.setMonth(cDate.getMonth() + months);

        return util.printd("mm/yyyy",cDate);

    }

}

Field level Javascript:

event.value = getPastDate("Today",-1);               results in 12/2018

event.value = getPastDate("Today",-2);               results in 12/2018

Please help!

Thank you!