The source notes (citation » "C" triangle symbol alongside title):

On December 24th, 2018, data for both the Retail sales, chained Fisher price index (2012) and Retail sales at 2012 prices (chained Fisher index) series were corrected for April 2018 through October 2018. 

In response, we have synchronized the series on Data Buffet. 

The series reside in the historical catalog (Canada » Consumer  » Retail trade » Sales summary) and are:

• WRCRTAM.ICAN = Retail trade: Sales, (Mil. Ch. 2012 CAD)
• WRJRTAM.ICAN = Retail trade: Sales, (Ch. Vol. Index 2012=100)

Because catalog locations are subject to change, the upper-right search box on DataBuffet.com provides a "find in catalog" mode that accepts a mnemonic.