Does showing competition brand in advertisement help is gaining buyers confidence?

Well, here are consultants views'

“Brand marketers should be especially encouraged to find owned advertising among the most trusted marketing formats,” said Randall Beard, global head, Advertiser Solutions at Nielsen.

“This form of advertising is trusted by nearly percent of consumers globally, which emphasizes the notion that marketers maintain the ability to control the messages about their brands in a way that consumers consider credible. This perceived credibility is a key component in advertising effectiveness.”

If trust is a critical strategic asset, as the Harvard Business Review argues, then marketers today need to understand how to build trust in a decentralized media environment in which consumer choice is almost infinite. In an era where privacy issues have the potential to derail consumer trust and dismantle the goodwill a brand has spent decades building, it is important to understand consumers' perception of privacy. Additionally, the tactics used by digital native brands in building and maintaining trust offer models for other companies attempting to connect with consumers in new channels and in unique ways (L. Jonathan,)

Depends on how you market your product, does it hurt your product or help? 

Not always. 

You see Coke and pepsi doing this all the time, but it doesn't always affect market share.

Source: https://www.quora.com/Are-there-any-long-running-advertising-rivalries-between-global-brands

I agree with Rami Abbas Sales Manager