hi, Experts

This is my first time to post my forum here, i am not the Oracle expert, thus, I really appreciate if anyone could help to answer my below questions.

1. can i create an existing datafile name for temp and applsysd and check on the reuse check box, i understand that the temp is for temporary storage and applsysd is for export and attachment, if i were to create a new datafile which the name already exist and with the reuse box check, will it overwrite my existing attachment ?

i am asking this question because this 2 tablespace has taken up a lot of hard disk space.

2. the free space shown in Toad and OEM is different for TEMP tablespace, TOAD say is is 0% free space, but in OEM says it only used up 19%, which one should i trust.