No-more-than-once per cell cycle initiation of DNA replication is a golden rule to maintain genome stability and guarantee cell survival. In our recent work we discovered that small genome fragments of about 200 bp are repeatedly synthesised at human DNA replication origins at the time of origin firing during S phase in normal cells. Rereplicated DNA fragments coincide physical and temporarily with replication origin activity, implying that their generation is intimately associated with the initiation of DNA replication. This unexpected finding may provide a new framework to study replication origin regulation.