将相等值的变量用作字典键会导致覆盖值（Python）

Question

I have a Python dictionary as below:

Mail_Dict = {
        MailList0 : CodeList0,
        MailList1 : CodeList1,
        MailList2 : CodeList2,
        MailList3 : CodeList3,
        MailList4 : CodeList4
}

The issue is when one of the MailLists have values that are the same as another MailList (ie: MailList0 = 'someone@email.com' and also MailList1 = 'someone@email.com' ), the keys are treated as equal and CodeList0 gets overwritten by CodeList1 , also making my dictionary shorter in the process.

Is there anyway to keep these separate? I would think that the same logic for below:

a=1
b=1

saving to separate memory addresses and being different from:

a=b=1

would apply here, but I guess that isn't the case =(

Thanks in advance.

Answer 1

If you want to create both the values of the same key in the dictionary, one solution would be to add the old value to a list and append the new value to the list.

Mail_Dict = {
    MailList0 : CodeList0,
    MailList2 : CodeList2,
    MailList3 : CodeList3,
    MailList4 : CodeList4
}

Now if you want to add MailList1 (which has the same value as MailList0) to the dictionary, check if MailList1 already is a list. if it is not a list make it into a list and then append the new value.

if(MailList1 in Mail_Dict):
    if (isinstance(Mail_Dict[MailList1],list)==False):
        Mail_Dict[MailList1] = [Mail_Dict[MailList1]

    Mail_Dict[MailList1].append(codeList1)