See the tests that start with the following:
"test_whiteSpaceDuringValid"
in the file:
daffodil-test/src/test/resources/edu/illinois/ncsa/daffodil/section05/simple_types/SimpleTypes.tdml

According to the spec, with textNumberCheckPolicy set to "lax", all whitespace is treated as zero. Based on this, we would expect "9 9" to parse as "909". This most likely seems to be an issue with the spec rather than the implementation.