if the value of double type elements contains 8 or more digits then it's not parsing as expecting (value is changed to 1.188E7.)

As per below article ,The  parseXML behaviour is changed from 7.3 onwards .

https://community.pega.com/support/support-articles/value-fields-soap-response-changed-parse-xml

I'm not clear with suggested resolution for best option.

Resolution

Correcting the WSDL so that data types match those that user wants to use in PRPC would be the best option.

Properties were created with Double and WSDL file is already defined with double type as well so what needs to be changed to fix the parsing error . Note :-Application is already in production and service response contains around 100 amount fields .