Add 'configuration' property to test export.
Instead of:
<testExecutions version="1">
<file path="TestFile_1">
<testCase name="test1()" duration="20517"/>
</file>
<file path="TestFile_1">
<testCase name="test1()" duration="20517"/>
</file>
</testExecutions>
the different test runs (or "configurations" in Xcode lingo) are now distinguishable.
<testExecutions version="1">
<file path="TestFile_1" configuration="iPhoneTests">
<testCase name="test1()" duration="20517"/>
</file>
<file path="TestFile_1" configuration="iPadTests">
<testCase name="test1()" duration="20517"/>
</file>
</testExecutions>