That is obvious. You should use different gates, towels, plates, bottles, everything, for your pets and children. If you have both pets and children in the same room, then having two different gates would be the ideal choice.
However, if you can’t afford two, it would be wise to buy at least one and position it so that it ensures your child gets the full room to play and grow in.
Do not, under any circumstances, use the same door for your child as that of your pet. They are both fundamentally different and might become carriers of bacteria and viruses.