RRSP tax receipts duplicated with RPP?

I have a 3% matching RRSP program through work.  3% is deducted from my salary weekly pay.  This 3% along with the company's matching 3% (which is not deducted from my pay) is then paid to an RRSP of my choice.  My work sends a cheque every month for the 6% contribution to my financial planner, who then puts this into my RRSP.  Seems like a bit of a complicated process.  On my T4 slip, Box 20 shows the total amount of RRSPs deducted from my pay (3%) plus any additional contributions I may have made throughout the year.  However, the issue is I get Official Income Tax Receipts for the entire 6% (plus additional contributions) and I get several of these throughout the year, each time a cheque is put into my RRSP account.  Do I total all of my Official Income Tax Receipts for my RRSP and deduct Box 20 of my T4 and report this as my RRSP contribution?  Even more confusing is that even though it's deducted weekly from my pay, the cheque may not make it to my financial planner in a timely manner.  How am I supposed to keep track of which year the contributions take place - by the tax receipts?