HTTP API V2 download range request: strange behaviour

Here are they (for smaller file):

GET https://content.dropboxapi.com/2/files/download?arg=%7B%22path%22:%20%22/test2.jpg%22%7D
{
 Authorization = "Bearer TOKEN";
 Range = "bytes=0-524287";
}

206
}
 "Accept-Ranges" = bytes;
 Connection = "keep-alive";
 "Content-Disposition" = "attachment; filename=unspecified";
 "Content-Length" = 524288;
 "Content-Range" = "bytes 0-524287/833408";
 "Content-Security-Policy" = sandbox;
 "Content-Type" = "application/octet-stream";
 Date = "Wed, 13 Apr 2016 20:38:59 GMT";
 "Dropbox-API-Result" = "{\"name\": \"test2.jpg\", \"path_lower\": \"/test2.jpg\", \"path_display\": \"/test2.jpg\", \"id\": \"id:hF-8wvxIrdAAAAAAAAAAVA\", \"client_modified\": \"2016-04-13T13:05:13Z\", \"server_modified\": \"2016-04-13T14:21:42Z\", \"rev\": \"10b645fbff27\", \"size\": 833408, \"media_info\": {\".tag\": \"metadata\", \"metadata\": {\".tag\": \"photo\", \"dimensions\": {\"height\": 1000, \"width\": 1000}}}}";
 Etag = "W/\"10b645fbff27\";
 "Original-Content-Length" = 524288;
 Server = nginx;
 Vary = "Dropbox-API-Arg, Authorization";
 "X-Content-Security-Policy" = sandbox;
 "X-Content-Type-Options" = nosniff;
 "X-Dropbox-Request-Id" = 64ce59cda4729419d32a1cca8148e020;
 "X-Robots-Tag" = "noindex, nofollow, noimageindex";
 "X-WebKit-CSP" = sandbox;
}

GET https://content.dropboxapi.com/2/files/download?arg=%7B%22path%22:%20%22/test2.jpg%22%7D
{
 Authorization = "Bearer TOKEN";
 Range = "bytes=524288-1048575";
}

206
{
 "Accept-Ranges" = bytes;
 Connection = "keep-alive";
 "Content-Disposition" = "attachment; filename=unspecified";
 "Content-Length" = 309120;
 "Content-Range" = "bytes 524288-833407/833408";
 "Content-Security-Policy" = sandbox;
 "Content-Type" = "application/octet-stream";
 Date = "Wed, 13 Apr 2016 20:40:32 GMT";
 "Dropbox-API-Result" = "{\"name\": \"test2.jpg\", \"path_lower\": \"/test2.jpg\", \"path_display\": \"/test2.jpg\", \"id\": \"id:hF-8wvxIrdAAAAAAAAAAVA\", \"client_modified\": \"2016-04-13T13:05:13Z\", \"server_modified\": \"2016-04-13T14:21:42Z\", \"rev\": \"10b645fbff27\", \"size\": 833408, \"media_info\": {\".tag\": \"metadata\", \"metadata\": {\".tag\": \"photo\", \"dimensions\": {\"height\": 1000, \"width\": 1000}}}}";
 Etag = "W/\"10b645fbff27\";
 "Original-Content-Length" = 309120;
 Server = nginx;
 Vary = "Dropbox-API-Arg, Authorization";
 "X-Content-Security-Policy" = sandbox;
 "X-Content-Type-Options" = nosniff;
 "X-Dropbox-Request-Id" = a45b71c7f42234a7271bed7df03b06c3;
 "X-Robots-Tag" = "noindex, nofollow, noimageindex";
 "X-WebKit-CSP" = sandbox;
}

-----------------------------------------------------------

GET https://content.dropboxapi.com/2/files/download?arg=%7B%22path%22:%20%22/test2.jpg%22%7D
{
 Authorization = "Bearer TOKEN";
 Range = "bytes=0-524287";
}

206
{
 "Accept-Ranges" = bytes;
 Connection = "keep-alive";
 "Content-Disposition" = "attachment; filename=unspecified";
 "Content-Length" = 309120;
 "Content-Range" = "bytes 524288-833407/833408";
 "Content-Security-Policy" = sandbox;
 "Content-Type" = "application/octet-stream";
 Date = "Wed, 13 Apr 2016 20:44:04 GMT";
 "Dropbox-API-Result" = "{\"name\": \"test2.jpg\", \"path_lower\": \"/test2.jpg\", \"path_display\": \"/test2.jpg\", \"id\": \"id:hF-8wvxIrdAAAAAAAAAAVA\", \"client_modified\": \"2016-04-13T13:05:13Z\", \"server_modified\": \"2016-04-13T14:21:42Z\", \"rev\": \"10b645fbff27\", \"size\": 833408, \"media_info\": {\".tag\": \"metadata\", \"metadata\": {\".tag\": \"photo\", \"dimensions\": {\"height\": 1000, \"width\": 1000}}}}";
 Etag = "W/\"10b645fbff27\";
 "Original-Content-Length" = 309120;
 Server = nginx;
 Vary = "Dropbox-API-Arg, Authorization";
 "X-Content-Security-Policy" = sandbox;
 "X-Content-Type-Options" = nosniff;
 "X-Dropbox-Request-Id" = 5538c11467902b81a6e7353a1d1768ed;
 "X-Robots-Tag" = "noindex, nofollow, noimageindex";
 "X-WebKit-CSP" = sandbox;
}

GET https://content.dropboxapi.com/2/files/download?arg=%7B%22path%22:%20%22/test2.jpg%22%7D 
{
 Authorization = "Bearer TOKEN";
 Range = "bytes=309120-833407";
}

206
{
 "Accept-Ranges" = bytes;
 Connection = "keep-alive";
 "Content-Disposition" = "attachment; filename=unspecified";
 "Content-Length" = 309120;
 "Content-Range" = "bytes 524288-833407/833408";
 "Content-Security-Policy" = sandbox;
 "Content-Type" = "application/octet-stream";
 Date = "Wed, 13 Apr 2016 20:46:00 GMT";
 "Dropbox-API-Result" = "{\"name\": \"test2.jpg\", \"path_lower\": \"/test2.jpg\", \"path_display\": \"/test2.jpg\", \"id\": \"id:hF-8wvxIrdAAAAAAAAAAVA\", \"client_modified\": \"2016-04-13T13:05:13Z\", \"server_modified\": \"2016-04-13T14:21:42Z\", \"rev\": \"10b645fbff27\", \"size\": 833408, \"media_info\": {\".tag\": \"metadata\", \"metadata\": {\".tag\": \"photo\", \"dimensions\": {\"height\": 1000, \"width\": 1000}}}}";
 Etag = "W/\"10b645fbff27\";
 "Original-Content-Length" = 309120;
 Server = nginx;
 Vary = "Dropbox-API-Arg, Authorization";
 "X-Content-Security-Policy" = sandbox;
 "X-Content-Type-Options" = nosniff;
 "X-Dropbox-Request-Id" = 4fc663ac6e844df8e9874e252f002373;
 "X-Robots-Tag" = "noindex, nofollow, noimageindex";
 "X-WebKit-CSP" = sandbox;
}