Influencer marketing platforms employ various methods to detect reused or duplicated content in order to maintain authenticity and credibility. These techniques involve:

1. Image Recognition: Leveraging advanced image recognition technology can help platforms identify duplicate images shared across multiple channels.

2. Content Hashing: This involves the algorithmic transformation of content into a unique identifier or ‘hash’. Once posted, the hash of the new content is compared with existing ones to detect duplicates.

3. Natural Language Processing: Advanced language analytics can be employed to analyze textual content for duplication. This can reveal similar phrasing or sentences reused in different posts.

4. Machine Learning: ML algorithms can be trained to understand patterns of duplicate content and identify them even if there are minor tweaks.

Platforms like Flinque, for example, use a combination of these methods to efficiently detect duplicated content in a proactive manner. This ensures that the content offered remains fresh and engaging.

To choose an influencer marketing platform, understanding how they handle content duplication can be an important factor, along with other considerations like their way of handling influencer discovery, campaign planning, performance tracking, and ROI measurement. Each platform comes with its own strengths, and the selection often depends on a team or brand’s specific needs.

It’s also crucial to remember that a portion of duplicate content, in moderation, can be acceptable in certain cases, especially if the message is consistent brand-wise, but excessive duplication may indeed reduce authenticity and audience engagement.