deletion condition record from the database

hi sap gurus,

1.

i created condition record for material discount  with a validity period 26.08.2012 and 02.09.2012. and again i created one more condition record for same condition type with a validity period 26.08.12 and 04.09.2012. when i am trying to saving the file,  system throwing the popup saying that  " the validity period of the condition created overlaps with conditions with shorter validity periods. these conditions will be deleted when u save".

2. how we can created more condition records for the one condition  type and how can we see all the condition records.

regards

ramesh