You can use the retail ink but... if either of the cartridges in the printer are Instant Ink cartridges the pages printed will be counted toward your monthly usage. Are the retail cartridges already installed in your printer? If so I would suggest using them up before installing the Instant Ink cartridges. Once either cartridge is exhausted and you need to install an Instant Ink cartridge the pages will be counted toward your monthly usage.
If the retail cartridges have not been opened you may want to keep them for later. If you cancel the Instant Ink program the Instant Ink cartridges will stop working at the end of the the billing cycle and will need to be replaced with retail cartridges. You may also consider keeping the cartridges for use in months when you may be printing more than usual to avoid going over your monthly allocation and any rollover pages you may have. [In my case the month of April is a busy printing time for me while printing and reviewing tax prep forms.]
If your page use is within the monthly Instant Ink there would be no reason to install one non-Instant Ink cartridges.
If you need to store opened cartridges for later use (either the retail cartridges while using Instant Ink cartridges or vice versa) then see the document here. Never put tape back on opened cartridges.
Bob Headrick, HP ExpertI am not an employee of HP, I am a volunteer posting here on my own time.
If your problem is solved please click the "Accept as Solution" button
If my answer was helpful please click "Yes" to the "Was this post helpful" question.