答: 可以

Multiple message-header fields with the same field-name MAY be
present in a message if and only if the entire field-value for that
header field is defined as a comma-separated list [i.e., #(values)].
It MUST be possible to combine the multiple header fields into one
"field-name: field-value" pair, without changing the semantics of the
message, by appending each subsequent field-value to the first, each
separated by a comma. The order in which header fields with the same
field-name are received is therefore significant to the
interpretation of the combined field value, and thus a proxy MUST NOT
change the order of these field values when a message is forwarded.

当且仅当这个name所对应的value是一组由逗号分隔的值. 并且这样的多个header可以合并到一个header中也不改变这个请求的语义

常见的例子: set-cookie, 经常见到一个response包含多个set-cookie的指令

按这个规定, request header中的 accept-encoding: gzip, deflate 似乎可以分成两个accept-encoding来发送