Tony is dead right, dont use a solvent based one as you could have problems. Is the Scotchgard protector you've got water based? if so no prob's.
The Guardsman protector is not available to anyone apart from retailers who apply it themselves (and sell warranties) and Safeclean franchisee's. The Guardsman product is available in water based and solvent based. There are suppliers that sell other protectors (both types) - either branded or non branded so shouldnt be an issue, but you will need both if your going to sell it across the board.
Tip:
Some protectors are sold as 'carpet protectors' and 'fabric protectors' - one will be solvent based and one will be water based. THIS IS TECHNICALLY WRONG and should be thought of as 'solvent protector' & 'water protector'. Subsequently the right protector should then be used dependent on what it is being applied to i.e. by assessing the correct fibre on both carpets and fabrics.