Stop template document fields merging

Hello

I am new to Adobe Sign and am using it for onboarding to send contracts of employment and new starter forms to new employees. 

When I send a contract of employment (I only insert a signature field for the employee to sign) I attach the two e-sign templates; one is our employee forms and the other is a separate payroll form. Both have been set up as a 'reuseable document'. All of the fields in these templates are data fields 'text input'

Seperately these templates work as I need them to but when sent together with the contract, information typed intothe data fields in employee forms template merge into the payroll template data fields. 

I don't want this to happen. Please can someone tell me how to stop the data fields copying information entered to data fields on the other templates - or what I'm doing wrong when setting up the templates with data fields. 

Many thanks.