HP Vectra XU5 Reference Manual page 18

Superscalar Architecture
The Pentium processor's superscaler architecture has two instruction pipelines and a
floating-point unit, each capable of independent operation. The two pipelines let the Pentium
execute two integer instructions, in parallel, in a single clock cycle. Using the pipelines
halves the instruction execution time and almost doubles the performance of the processor,
compared to an Intel486 microprocessor of the same frequency.
Frequently, the processor can issue two instructions at once (one instruction to each
pipeline). This is called instruction pairing. Each instruction must be simple. One pipeline will
always receive the next sequential instruction of that issued to the other pipeline.
Vectra XU Technical Reference System Overview 18