No, there is no requirement to use the same product linking units R106, R107 and R108 as each unit is stand-alone. You can use the same product if you wish to however.
You should be cautious however if candidates are using the outcome produced for one unit (e.g. R107) as the activity for the next unit (e.g. R108) as this could disadvantage the candidate if they start off with a weak activity. In these cases, it would be sensible to have a new proven activity for them to start from.