Http requests are made by non-user requests using the Dalvik user agent

Question

I noticed in my magazines that every time some of my registered users make a request, a second “shadow” request appears. The second request has the same IP address as the "normal" request, but a reduced header. Each time this opens a new session.

I noticed that this is common for tables.

Any ideas on what causes this?

Request Header:

host = www.example.com
connection = keep-alive
accept = text / html, application / xhtml + xml, application / xml; q = 0.9, image / webp, * / *; q = 0.8
Upgrade-Insecure-Requests = 1
user-agent = Mozilla / 5.0 (Linux; Android 5.1.1; Lenovo YT3-X50F Build / LMY47V) AppleWebKit / 537.36 (KHTML, like Gecko) Chrome / 47.0.2526.83 Safari / 537.36
referer = https: //www.example.com/auth/xyz
accept-encoding = gzip, deflate, sdch
accept-language = en-GB, en-US; q = 0.8, en; q = 0.6
cookie = JSESSIONID = XXXXX; _gat = 1; _ga = GAXXXXXX

Shadow request header:

Headers = user-agent = Dalvik / 2.1.0 (Linux; U; Android 5.1.1; Lenovo YT3-X50F Build / LMY47V)
host = www.example.com
connection = Keep-Alive
accept-encoding = gzip