SHarePoint document checkout issue

Hi Experts,

I am facing some strange issue with document checkout in SP2013.

There are two user's:

First user checkout doc and start editing in web app.

At the same time, Second user opens the doc and try to edit in word web app, receives a notification stating "Someone else has workbook checked out or opened in excel: it can't be edited in browser." Click "OK" and try to open in Desktop application (MS-EXCEL). Second user got below pop up:



After clicking "OK" by second user.

First user, receives below alert popup:

and clicking on Reload by First user, all the changes, updated by First user lost.

How can i Fix this ? 

Thanks,

Mahesh

Mahesh Sinha