Yes. It is a slip coach, for instance 16343 and 16349 trains are run together as a single rake from Thiruvanathapuram to Shoranur. From there former goes to Palakkad and the latter to Nilambur. read more
Here's a simple statistic - the Indian Railways puts out about 50,000 (that's right - fifty thousand) design changes in ONE year (I repeat, in a year) on coach design alone. Some are for completely new design of coaches, some are upgrades for older designs. read more