Joiner with Parcial information

Hello im having a problem with a joiner where one information is complete while the other was written by a person so it has been shorten but is kinda random, the info seen to be exact to a certain point but it always drops

example

RCV 100 X 150000 P NAT = RCV 100 X 150000 P NATURAL PVC 30 60

i would just use the string manipulator substr( , , ) but the problem is that they are kinda random so some time i will need more letter and some times i will need less

is there a way to use some kind of joiner where it reads both sides and if match until a certain point i can join or that is impossible and i HAVE to have the exact cutting point?

thank you for your time