breeding different types of terrapins

Question
QUESTION: hi, i have a yellow bellied slider and a black knobbed sawback terrapin both are under a year old.
the slider has been recently started exhibiting signs of trying to mate with the sawback.
(swimming around the sawbacks head with both front feet stretched out in front of him. i discovered this on google.)
what i cant find out is if they're likely to produce babies or if i can just leave them to it and they'll just mate and nothing will come of it.
im sorry if this seems like a stupid question but if this is likely to cause them to fight then i'd rather know so i can transfer them to different tanks.
thankyou for your consideration.

ANSWER: Black Knobbed "Map turtle". They may mate, and produce offspring, though they should not be allowed at that age. The female may also reject a male of another genus. What you should be concerned about is the male continually harassing the female and preventing her from eating or getting rest, which will stress her.

---------- FOLLOW-UP ----------

QUESTION: thankyou for replying.
It seems i was misinformed by the chap who sold them to us.

im going to keep an eye on them but i have another tank ready if it seems the sawback is suffering.

again thankyou for taking the time to reply.

Answer
Both of these aquatic turtles are native here in the states, and there is hybridization in the wild between genera sometimes. Though if appearances are too drastic, a female will reject the male. That won't stop him from harassing her though.

I have seen claims online of captive breeding between these two, and some examples in the wild which may be hybrids of these two. I do not assume that offspring would be fertile mind you, but not even an academically pedigreed herpetologist would be so sure to assume they could not mate and produce offspring at all! Only a vendor could be so bold and ignorant with his assumptions.