I am using tag in multi field component with .hidden group, when first time I am using this component, its working fine and saving tag values but when next time I am editing this component and adding new tag in new field then its saving only last field(or last selected) tag value and removed previous tag values from component.
attachment:component properties, jsp , dialog
When working with Multifields - you need to code the controls inside each multifield. Look at this article where we talk about nested multifields.
So if you want to use a TagInputField xtype in a multifield - you need to code that data type in a JS file - similar to the JS file that is shown in the above article.
Have you done that? If the code is not correct - the data will not save.