End Client Change in same MSA - H1b Stamping question

[Sun God]

hi all,
I am on my h1b and working through the EVC model. Got my h1b visa approved when working for end client A. Few months later moved to end client B in the same MSA. Have about a year left on h1b and need to go for stamping. Is an amendment needed in my case? Did someone have a similar situation and how did you handle it?

Any help will be appreciated.