Conditional fields do not disappear when option changed

I’m on the pro version specifically to use the conditional formatting for the fields. I need to do a conditional form such that the user’s choice in the first field would result in two drop down fields appearing. The choice of which two drop down fields appearing would depend on the choice in the first field.

However when I do this and the user changes his mind for the first field, the old fields generated by the first choice do not disappear. Instead two new fields will appear resulting in 4 fields in total.

Is this a bug? Anyway to resolve this?

Thanks

http://ww.wp.xz.cn/extend/plugins/visual-form-builder/