Let's make this clear amd unambiguous, employers and recruitment agents will generally not pay you for your value. They'll spend time on multiple interviews, psych tests, references, technical tests to understand your competency and then try and offer you the same or less than what you are currently getting paid.
It's a common situation that people aren't offered more money from current employers unless they threaten to resign. Employers rarely understand that an employee's value is not just their skill sets however also includes corporate intellectual property and internal customer and internal relationships that help you get the job done.
So how do you manage salary negotiation ? It's simple - any questions about current salary - your answer is 'Let's talk about the value you place on the role and current industry standards for my position'. It's always a risk that the employer walks away however it's the one of the few ways to stop wage deflation in your profession.
Another method is to ask what it would it cost to fill the role with a contractor with a similar skillset - that tends to reset the value proposition of a role in salary negotiations. Salary negotiation is an art and professional recruiters are skilled at manipulating your expectations on salary. Don't be unrealistic - know your value and industry salary standards as compared to your experience and skillsets.