Off topic:Question About Ilumina'S Bridge Amplification In Next Generation Sequencing

Question

[Alby]

Hello

In illumina's NGS sequencing, first DNA to be sequenced are chopped up, attached to the specific adapter sequences, and denatured. And then, single stranded fragments are then poured into lanes in flowcell. And bridge amplification begins from here. like this: http://i.imgur.com/WQKDb.png

My question is, How do you make sure to prevent the situation like this?

http://i.imgur.com/EfY5o.png

In other words, how do you prevent different fragments fall into the same region? In the first diagram, the homogeneous cluster forms after rounds of PCR, which consist of original fragment and its reverse complements. But if different fragments were present so closely in the same region, wouldn't the cluster be heterogeneous?