I've received a few of these and the hp no. is the same although the charity group stated is different. The format of the leaflet is also the same.
I suspect the ppl involved might be selling the stuff and pocket the money instead of donating to charity.
So I wrote to the charity group and this is their response:
The Children's Heart Foundation
Hi. Thank you for bringing this to our attention. That is our logo and mission statement, but we have no knowledge of any fundraising efforts in Singapore. We fund medical research, we do not collect (or distribute) the types of items that they have listed. Therefore this donation collection is not associated with our organization. Please let us know if you have any questions.