No, theyre expecting you to continue to use the left hand photo side that was on your old B. This saves you getting a new photo etc, and a trip to the Commune just to pick it up.
It does mean the counterfoil number for the paper document will be inconsistent, but this is not an issue as your other central and conatonal reference numbers (beginning with VD etc) will be valid.
The most important thing is that your personal details are correct including your date of entry to CH.
For perspective: some applicants need to do language tests, extended credit and criminal reference checks etc. and wait 10 years to even be eligible to apply for the document you have received relatively straightforwardly.