API 1104 includes all the required mechanical tests needed to qualify a WPS. I do not recall a requirement for an "all weld metal" tensile test.
There is a point to remember with regards to the tensile test requirements of API; they use the load at failure divided by the original cross sectional area of the test sample. This is different than the UTS as determined by ASME/AWS/ and military standards that use the maximum load divided by the original cross sectional area of the test specimen.
