Melting point of aspirin, contradicting sources
Wolfram company doesn't conduct any experimental determinations of physical constants for chemical compounds and uses literature data sources.
The webpage for ChemicalData Source Information lists numerous sources of chemical information used by the company's products, including Wolfram Alpha.

Wolfram Alpha Knowledge Database is linked with 87th ed. (2006) of CRC Handbook of Chemistry and Physics (m.p. $\pu{135 °C}$), whereas Wikipedia cites newer 92nd ed. (2011) of CRC Handbook of Chemistry and Physics (m.p. $\pu{136 °C}$).



Obviously, Wolfram's sorting algorithm preferred another data source despite it's quoting the CRC Handbook.
Why and how it did that cannot be answered as the server-side engine is proprietary.

Note that even newer 97th ed. (2017) of CRC Handbook of Chemistry and Physics adds measurement error of $\pu{4 °C}$ (m.p. $\pu{136(4) °C}$).
The difficulty of determining the exact value probably arises from the fact that at that temperature range thermal decomposition already begins, which is reflected in m.p. dependence on heating rate and atmosphere and melt solidifying at lower temperatures (down to $\pu{118 °C}$ [1, table 3.4]).

References


Aspirin and Related Drugs; Rainsford, K. D., Ed.; CRC Press; Taylor &amp; Francis: London, 2004. ISBN 978-0-7484-0885-6.